From msclark@ucdavis.edu Fri Feb 13 01:04:24 1998 Date: Wed, 11 Feb 1998 15:53:43 -0800 (PST) From: Sean Clark To: sanet-mg@shasta.ces.ncsu.edu Subject: Cation balancing in organic farming Soil Saneters: I am seeking some common ground and understanding on an issue which seems to be of extreme importance to many organic farmers and consultants but given little attention by academic scientists - that is soil cation balancing and the importance of calcium (Ca) in soil structure. Time and again, when speaking with organic farmers and the consultants who serve them, I find the importance of cation balancing and soil Ca come to the center of the conversation. In lay terms, the basic idea is that inadequate exchangeable Ca results in poor soil structure, characterized by "tightness" because the amount of pore space for air is less than optimal. Consequently, root health is compromised and nutrient availability and uptake reduced. A general rule often given is that the ratio of Ca to magnesium (Mg) should be about 5-7 to 1. If it is less - you need to add Ca. As the research manager of a long-term study/comparison of organic, low-input, and conventional farming systems at the Univ. of California at Davis, I am sometimes criticized by these folks for giving inadequate attention to this issue. In this study, all of the farming systems are managed according to "best farmer management" strategies - which are determined by a group of academic and Extension researchers, Extension farm advisors, and farmers. Admittedly, we have not made or altered any management practices in this study based on soil Ca:Mg ratios. Consequently, some organic farmers and consultants argue that the organic system in this study is being shortchanged because we have not given the soil Ca:Mg ratio proper attention. When I ask where I can get more information on this matter I am usually referred to William Albrecht and his Papers. He published a number of studies during the 1920-1940s in the J. Amer. Soc. Agron. but I have found that his name now seems to be reserved for the pages of Acres USA (not to diminish Acres USA). My point is that I find no recognition or ackowledgement of him or his work in basic or advanced textbooks on soil science and fertility management or among research scientists - even among those who are doing research on organic and low-input agriculture. It seems that Albrecht is to many in the organic movement what Stinner is to the Biodynamic movement. I see some people adhere to his "Papers" with almost religious conviction. Getting back to my problem: The Ca:Mg ratios of the soils at this study site are nowhere near 5-7:1. In fact, they are less than 1:1. The Ca:Mg ratio in the organic system in this study is significantly (statistically) higher than that of the conventional system due to the Ca in the composted and aged manures that have been added over the years, but in absolute terms the difference is still quite small. There is a clear difference, however, in water infiltration rates between the organic and conventional systems. Rates are much greater in the organic system (which we presume is due largely to the higher soil organic matter levels in this system). Therefore, if any of the farming systems in this study is in need of management to remedy a soil structural problem it would be the conventional system. And, indeed, the group has discussed applying gypsum to improve infiltration rates in the conventional system. However, the claims go beyond simply improving soil structure to enhance root growth and plant health. I am also told that the nitrogen (N)-use efficiency of the organic system would improve and that disease severity would decline with an increase the Ca:Mg ratio. The latter doesn't particularly interest me right now because diseases have not been a serious yield-limiting factor in any of the farming systems. But, the potential to improve N management in the organic system does. As many studies comparing organic to conventional systems have found, the release of mineral N from organic amendments and soil organic matter and uptake by the crop are not always predictable. Hence, we generally apply considerably more N to 'nitrophilic' crops in the organic system to compensate for unpredictable N mineralization and make up for that taken up by soil microbes or weeds. But losses from the organic system (due to leaching, denitrification, and volatilization) are not any greater in the organic compared to the conventional system. Therefore I do not see how the addition of Ca would reduce the amount of N which needs to be added - even over a long term. Ouestions: Are Albrecht's views accepted by "mainstream" soil scientists or are his ideas considered fringe? Do any university laboratories adhere to any of his concepts? Can anyone direct me to studies on Ca:Mg ratios and cation balancing (I have found very few)? Also, do any growers on the list have personal experiences with using soil Ca:Mg ratios in fertility or disease management ? Thanks in advance, Sean M. Sean Clark Research Manager Sustainable Agriculture Farming Systems Project Department of Agronomy and Range Science University of California Davis, CA 95616 msclark@ucdavis.edu TEL:(916) 752-2023 FAX:(916) 752-4361 To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". From rw17@umail.umd.edu Fri Feb 13 01:05:05 1998 Date: Wed, 11 Feb 1998 22:02:09 -0600 From: "Raymond R. Weil" To: Sean Clark Cc: sanet-mg@shasta.ces.ncsu.edu Subject: Re: Cation balancing in organic farming Sean, You raise a subject that has interested me for quite some time, as I, too have often come across famers, salespeople and consultants who swear by Albrecht's theories of cation balance. Unfortunately, none of the people I have asked has been able (or willing) to provide any scientific basis or even replicated, reliable data to support their contentions. I have been told that they have "happy customers" not data. None of the farmers I have talked to have even tried replicated strips to test the high - Calcium system effects, so they might have been happy without it, too. Certainly there is truth to the idea that Ca plays a critical role in soil flocculation and plant (and animal) nutrition. The cation exchange complex in mosat soils is dominated by Calcium ions (at least among the non-acid cations). If the ratio of divalent to monovalent ions gets unusually low, soil structure, permeability, and infiltration certainly suffer. While sodium is most commonly to blame, there are documented reports of excessive potassium applications having similar, but less dramatic effects. The effect of excessive Magnesium and Potassium on Calcium uptake by plants is also well-documented, and to be expected from charge balance considerations, among others. Actual Ca deficiency is quite rare, and occurs almost exclusively on very acid soils where it is difficult to distinguish from Aluminum toxicity. In solutions that are extremely low in Ca, other metal ions (such as Mg) actually become toxic to plant roots, for the Ca is needed to maintain cell membrane stability. Sean, if I recall, your rotations include processing tomato, a plant that is very susceptible to low Ca (which combined with uneven water) can cause blossum end-rot. Has this ever occured on your plots? The calcium content of animal forages is also quite important to animal health. Grass tetany is an extreme case, sometimes associated with excessive potassium and reduced magnesium and calcium intake. likewise, earthworms have a definite requirement for Calcium in their environment, the amount depending on the species. Calcium probably also can enhance general heterotrophic microbial decomposition, as well as certain specific microbial species (some Rhizobia and nitrifiers come to mind). However, in most studies the effects of Calcium and pH are confounded. Lab and field evidence would indicate that pH is the overriding factor. However, I am aware that some consultants recommend applying calcium even when pH is above 7.0. In humid regions this is generally not good advice, as calcium in the form of limestone would result in too high a pH and thus micronutrient deficiencies and other problems. However, in humid regions where pH has been long maintained with dolomitic limestone (about 35% Mg), the ratio of Mg to Ca can become an issue of concern. Magesnium has considerably less flocculating ability than does Calcium, so I would recommend calcitic limestone in most cases, unless available Mg by soil test is below "medium". Low Magnesium is a problem more commonly than high. For example, Magnesium saturation should general exceed that of potassium by a comfortable margin (say 2.5:1 or 3:1 or higher). If the ratio gets close to 1:1, or certainly if there is more exchangeable K than Mg, deficiencies of Mg are quite likely in many plants. This rarely happens in nature (except in some humid tropical soils), but can result from heavy K fertilizer (or even poultry manure) application on some soils. Except for those which evolved on serpentine-derived soils, most plants are adapted to a considerable predominace of exchangeable Ca over Mg and other non-acid cations. To a large degree, plant roots can selectively take up what they need, as evidenced by internal plant composition which can difer greatly from the composition of the soil solution. However, extremely out of balance soils can certainly affect plant uptake. I have seen no evidence that there is any problem with ratios are disparate as 3:1 or 10:1 (Ca : Mg) , but clearly the 1:1 or lower that you report could be a problem. So the upshot is, check those Ca and Mg saturation numbers again. Also, check the plant leaf tissue. Is the Ca level unusally low? If there really are about equal moles of charge from the two cations, yes, some gypsum might be in order (in both organic and conventional systems). But that is treating the symptom. I'd want to know where all that Mg is (or was) coming from. Magnesium uptake by corn and other grasses (not woody trees, or tomato leaves, though) is not too different from that of Calcium, so depletion rates are unlikely to explain it unless you have been removing all the tomato vines for years (the leaves and stems may be 5 to 10 times as high in Ca as in Mg, but the fruits have little of either Ca or Mg --but are vey high in K). Are your soils derived from unusually Mg-rich parent materials? I am sorry this "essay" has been so rambling. I wish I had time to look up all the refernces for you. Many of the above considerations are discussed in 11th edition (and will be more so in the up-coming 12th edition) of The Nature and Properties of Soils (by Nyle Brady and myself). Do let us know what you find out on your soil and tissue analyses. (Oh yes, if you do apply gypsum, for all our sakes, can you please split the plots or try a side experiment so we can get some data on this!?) Good luck, Ray Weil Sean Clark wrote: > Soil Saneters: > > I am seeking some common ground and understanding on an issue which seems to > be of extreme importance to many organic farmers and consultants but given > little attention by academic scientists - that is soil cation balancing and > the importance of calcium (Ca) in soil structure. > > Time and again, when speaking with organic farmers and the consultants who > serve them, I find the importance of cation balancing and soil Ca come to > the center of the conversation. In lay terms, the basic idea is that > inadequate exchangeable Ca results in poor soil structure, characterized by > "tightness" because the amount of pore space for air is less than optimal. > Consequently, root health is compromised and nutrient availability and > uptake reduced. A general rule often given is that the ratio of Ca to > magnesium (Mg) should be about 5-7 to 1. If it is less - you need to add Ca. > > As the research manager of a long-term study/comparison of organic, > low-input, and conventional farming systems at the Univ. of California at > Davis, I am sometimes criticized by these folks for giving inadequate > attention to this issue. In this study, all of the farming systems are > managed according to "best farmer management" strategies - which are > determined by a group of academic and Extension researchers, Extension farm > advisors, and farmers. Admittedly, we have not made or altered any > management practices in this study based on soil Ca:Mg ratios. > Consequently, some organic farmers and consultants argue that the organic > system in this study is being shortchanged because we have not given the > soil Ca:Mg ratio proper attention. > > When I ask where I can get more information on this matter I am usually > referred to William Albrecht and his Papers. He published a number of > studies during the 1920-1940s in the J. Amer. Soc. Agron. but I have found > that his name now seems to be reserved for the pages of Acres USA (not to > diminish Acres USA). My point is that I find no recognition or > ackowledgement of him or his work in basic or advanced textbooks on soil > science and fertility management or among research scientists - even among > those who are doing research on organic and low-input agriculture. It seems > that Albrecht is to many in the organic movement what Stinner is to the > Biodynamic movement. I see some people adhere to his "Papers" with almost > religious conviction. > > Getting back to my problem: The Ca:Mg ratios of the soils at this study site > are nowhere near 5-7:1. In fact, they are less than 1:1. The Ca:Mg ratio > in the organic system in this study is significantly (statistically) higher > than that of the conventional system due to the Ca in the composted and aged > manures that have been added over the years, but in absolute terms the > difference is still quite small. There is a clear difference, however, in > water infiltration rates between the organic and conventional systems. > Rates are much greater in the organic system (which we presume is due > largely to the higher soil organic matter levels in this system). > Therefore, if any of the farming systems in this study is in need of > management to remedy a soil structural problem it would be the conventional > system. And, indeed, the group has discussed applying gypsum to improve > infiltration rates in the conventional system. > > However, the claims go beyond simply improving soil structure to enhance > root growth and plant health. I am also told that the nitrogen (N)-use > efficiency of the organic system would improve and that disease severity > would decline with an increase the Ca:Mg ratio. The latter doesn't > particularly interest me right now because diseases have not been a serious > yield-limiting factor in any of the farming systems. But, the potential to > improve N management in the organic system does. As many studies comparing > organic to conventional systems have found, the release of mineral N from > organic amendments and soil organic matter and uptake by the crop are not > always predictable. Hence, we generally apply considerably more N to > 'nitrophilic' crops in the organic system to compensate for unpredictable N > mineralization and make up for that taken up by soil microbes or weeds. But > losses from the organic system (due to leaching, denitrification, and > volatilization) are not any greater in the organic compared to the > conventional system. Therefore I do not see how the addition of Ca would > reduce the amount of N which needs to be added - even over a long term. > > Ouestions: > > Are Albrecht's views accepted by "mainstream" soil scientists or are his > ideas considered fringe? Do any university laboratories adhere to any of > his concepts? Can anyone direct me to studies on Ca:Mg ratios and cation > balancing (I have found very few)? Also, do any growers on the list have > personal experiences with using soil Ca:Mg ratios in fertility or disease > management ? > > Thanks in advance, > > Sean > > M. Sean Clark > Research Manager > Sustainable Agriculture Farming Systems Project > Department of Agronomy and Range Science > University of California > Davis, CA 95616 > msclark@ucdavis.edu > TEL:(916) 752-2023 > FAX:(916) 752-4361 > > To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". > To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command > "subscribe sanet-mg-digest". [Part 2, "Card for Ray R. Weil" Text/X-VCARD 14 lines] [Unable to print this part] From sgroff@epix.net Fri Feb 13 01:05:19 1998 Date: Wed, 11 Feb 1998 23:29:55 -0500 From: Steve Groff To: Sean Clark Cc: sanet-mg@shasta.ces.ncsu.edu Subject: Re: Cation balancing in organic farming Sean, 10 years ago, my Ca - Mg ratios averaged 3:1. Now after deliberate stategies to better balence my soil they read 7:1. I did not do any direct comparisons (I wish someone would) but I do have records that indicate that my soil is now producing higher yielding and better quality crops. Soil stucture is has also noticibly improved. Sorry I don't have hard numbers, but I tend to think there is something to getting the Ca: Mg ratios to 7:1. -- "New Generation Cropping Systems": the cutting edge of sustainable agriculture http://www.cedarmeadowfarm.com Steve Groff Cedar Meadow Farm 679 Hilldale Rd Holtwood PA 17532 USA Ph. 717-284-5152 To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". From Alenson.Chris.CJ@bhp.com.au Fri Feb 13 01:05:36 1998 Date: Fri, 13 Feb 1998 12:35:51 +1100 From: "Alenson, Chris CJ" To: Sean Clark Cc: "'sanet-mg@ces.ncsu.edu'" Subject: RE: Cation balancing in organic farming [The following text is in the "iso-8859-1" character set] [Your display is set for the "US-ASCII" character set] [Some characters may be displayed incorrectly] Sean, You have touched on an interesting area. As someone who has studied the work of Albrecht there is no doubt that cation balance and appropriate organic matter management is the key to fertility management as he saw it. Some texts utilised in Australia in soil science refer to cation balance along the lines that Albrecht suggested but the source of that information is not referenced. Much of the early work on cation exchange is referred to in clay mineralogical texts. For instance Thompson in 1850 was perhaps one of the first to systematically studied cation exchange. Way in 1850 also showed that cation exchange was restricted to the clay fraction and that it was connected with the silicate compounds in the soil. From this date on and especially entering into the period when Albrecht did his work much research was done in expanding the knowledge base of cation and base exchange. Enter Albrecht whose basic work in stripping the clay fraction of nutrients and then adding them back in set proportions to provide the most favorable plant growth was at that time the cutting edge of research. You are correct in stating that very little information exists in the soil science literature which looks at the effect of balancing the cations in the soil. Perhaps it is the nature of research that insufficient funds and time exists to study such a phenomena. Although I regard myself as mealy a student of soils I have studied the conventional soil science texts and also very thoroughly the work of Albrecht. What I find compelling about Albrecht's work is the depth of knowledge that this man possessed of natural systems and the interaction that occurs between these systems. He was not content to study just what nutrients should be added to soils in what proportions to provide the best plant growth but then took this plant material and fed it to animals to ensure that the nutrient balance would provide the most appropriate feed to give these animals health and fertility over successive generations. His papers on calcium, legumes and protein building was at the time pretty new in soil science terms. Amongst other things the correct addition of calcium prevented dampening off in seedlings and resulted in stronger cell wells which I guess would assist in minimising fungal problems and possibly be less prone to insect damage? Nitrogen supply via legumes was to Albrecht secondary to establishing the correct balance of calcium, magnesium and potassium. The building up of organic and humic material in the soil with the concomitant increase in microbial biomass ultimately increases the nitrogen reserves of the soil and is an important part of the Albrecht scheme of things. >From my literature research there are not too many soil scientists that have spent their life following this line of research. Herein lies the problem and why not too many other soil scientists either know or recognise Albrechts work. Over the last decade or more fragmented compartmentalised research has not been conducive to the study of the many overlapping fields in soil science. Have soil scientists either the will or the research money to follow such extensive lines of research? Albrecht believed (and I am sure we all do) that due to natural geological processes and human activities the depletion of nutrients from soils lowered soil fertility to the extent where if the correct addition of nutrients was not made the products from these agricultural systems would be lowered in quality. The addition of inorganic elements sometimes runs contrary to some thinking in the organic movement where low input and in some cases closed systems are the order of the day. The reason why many in the organic movement have adopted Albrecht's work is the overriding emphasis on the Healthy soil->Healthy Plants->Healthy Animals hypothesis. That afterall is one of the key goals of organic farming. As a consultant and a grower I have utilised Albrecht's work along with what I was taught in conventional soil science. That information married with the techniques and practices from organic agriculture appear to be able to provide a good foundation for sustainable agricultural practices. One of the many things I look at in a soil analysis is the total cation exchange, it gives me an indication of what nutrients are able to be held in the soil available for plant growth. Knowing the clay mineralogy is also helpful as far as indicating how degraded the soil is likely to be in the context of the weathering cycle. Other than adding high cation exchange clays to the soil (not very practical for the average farmer) the addition of organic matter to provide humus is the only other way of increasing the exchange capacity of a soil. Balancing nutrient elements as suggested by Albrecht has been a succesful management tool and until I can find a soil scientist that has done similar research and demonstrates a different set of ratios that should be used I guess I will continue along these lines. I am sure he is not the only soil scientists that has provided inspiration to agriculturalists, but his papers/books are not a bad start for those who are interested in expanding their knowledge in this field. I look forward to further comment on this fascinating topic. Chris Alenson Technical Adviser Organic Advisory Service Organic Retailers & Growers Association of Australia ---------- From: Sean Clark[SMTP:msclark@ucdavis.edu] Sent: Thursday, 12 February 1998 9:54:am To: sanet-mg@shasta.ces.ncsu.edu Subject: Cation balancing in organic farming Soil Saneters: I am seeking some common ground and understanding on an issue which seems to be of extreme importance to many organic farmers and consultants but given little attention by academic scientists - that is soil cation balancing and the importance of calcium (Ca) in soil structure. Time and again, when speaking with organic farmers and the consultants who serve them, I find the importance of cation balancing and soil Ca come to the center of the conversation. In lay terms, the basic idea is that inadequate exchangeable Ca results in poor soil structure, characterized by "tightness" because the amount of pore space for air is less than optimal. Consequently, root health is compromised and nutrient availability and uptake reduced. A general rule often given is that the ratio of Ca to magnesium (Mg) should be about 5-7 to 1. If it is less - you need to add Ca. As the research manager of a long-term study/comparison of organic, low-input, and conventional farming systems at the Univ. of California at Davis, I am sometimes criticized by these folks for giving inadequate attention to this issue. In this study, all of the farming systems are managed according to "best farmer management" strategies - which are determined by a group of academic and Extension researchers, Extension farm advisors, and farmers. Admittedly, we have not made or altered any management practices in this study based on soil Ca:Mg ratios. Consequently, some organic farmers and consultants argue that the organic system in this study is being shortchanged because we have not given the soil Ca:Mg ratio proper attention. When I ask where I can get more information on this matter I am usually referred to William Albrecht and his Papers. He published a number of studies during the 1920-1940s in the J. Amer. Soc. Agron. but I have found that his name now seems to be reserved for the pages of Acres USA (not to diminish Acres USA). My point is that I find no recognition or ackowledgement of him or his work in basic or advanced textbooks on soil science and fertility management or among research scientists - even among those who are doing research on organic and low-input agriculture. It seems that Albrecht is to many in the organic movement what Stinner is to the Biodynamic movement. I see some people adhere to his "Papers" with almost religious conviction. Getting back to my problem: The Ca:Mg ratios of the soils at this study site are nowhere near 5-7:1. In fact, they are less than 1:1. The Ca:Mg ratio in the organic system in this study is significantly (statistically) higher than that of the conventional system due to the Ca in the composted and aged manures that have been added over the years, but in absolute terms the difference is still quite small. There is a clear difference, however, in water infiltration rates between the organic and conventional systems. Rates are much greater in the organic system (which we presume is due largely to the higher soil organic matter levels in this system). Therefore, if any of the farming systems in this study is in need of management to remedy a soil structural problem it would be the conventional system. And, indeed, the group has discussed applying gypsum to improve infiltration rates in the conventional system. However, the claims go beyond simply improving soil structure to enhance root growth and plant health. I am also told that the nitrogen (N)-use efficiency of the organic system would improve and that disease severity would decline with an increase the Ca:Mg ratio. The latter doesn't particularly interest me right now because diseases have not been a serious yield-limiting factor in any of the farming systems. But, the potential to improve N management in the organic system does. As many studies comparing organic to conventional systems have found, the release of mineral N from organic amendments and soil organic matter and uptake by the crop are not always predictable. Hence, we generally apply considerably more N to 'nitrophilic' crops in the organic system to compensate for unpredictable N mineralization and make up for that taken up by soil microbes or weeds. But losses from the organic system (due to leaching, denitrification, and volatilization) are not any greater in the organic compared to the conventional system. Therefore I do not see how the addition of Ca would reduce the amount of N which needs to be added - even over a long term. Ouestions: Are Albrecht's views accepted by "mainstream" soil scientists or are his ideas considered fringe? Do any university laboratories adhere to any of his concepts? Can anyone direct me to studies on Ca:Mg ratios and cation balancing (I have found very few)? Also, do any growers on the list have personal experiences with using soil Ca:Mg ratios in fertility or disease management ? Thanks in advance, Sean M. Sean Clark Research Manager Sustainable Agriculture Farming Systems Project Department of Agronomy and Range Science University of California Davis, CA 95616 msclark@ucdavis.edu TEL:(916) 752-2023 FAX:(916) 752-4361 To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". From msclark@ucdavis.edu Fri Feb 13 01:05:51 1998 Date: Thu, 12 Feb 1998 19:29:54 -0800 (PST) From: Sean Clark To: sanet-mg@shasta.ces.ncsu.edu Subject: More on Cation Balancing More on Cation Balancing... First of all, thanks to those of you who responded to my inquiry on cation balancing and Ca:Mg ratios, either via the list or directly. With the assistance of Ray Weil's comments and some information from Bill Liebhardt, I've been able to dig up some (not all) answers to questions I raised and others that Ray brought up in his first response. It turns out that there has been some research at land-grant universities to address this issue. Bill Liebhardt conducted research in Delaware during the 1970s to test what he called the "Basic Cation Saturation Ratio Concept" for field crops. His justification for the research was that two approaches to soil test interpretation were in use: 1) sufficiency levels of available nutrients (SLAN) and 2) basic cation saturation ratios (BCSR). The first was/is used by university laboratories while the latter was/is used by commercial laboratories. In Liebhardt (1981) he reviews some of the early literature on the concept and credits Firman Bear and other researchers from New Jersey during the 1940s with proposing it. I looked up some of the Bear et al. references and found William Albrecht was indeed mentioned. However, Albrecht was cited not as the founding father of the concept but rather for justification of some laboratory methods. In these papers by Bear and associates, the ideal soil was defined as having an exchange complex saturated with 65% Ca, 10% Mg, 5% K, and 20% H (Bear and Toth 1945). This is based upon greenhouse studies with alfalfa in an array of New Jersey soils. Liebhardt went on to cite other studies from the 1930s and 40s that found no relationship between Ca:Mg ratios and yield. And from his own research, Liebhardt concluded, "wide ranges of Ca:Mg satisfy nutrient requirements of corn and soybean" provided the pH is maintained at 6 or slightly less to prevent Mn deficiency. Similarly, Eckert and McLean (1981) conducted a growth chamber study with German millet and alfalfa under a range of cation ratios and concluded that "balance of cations in the soil was unimportant, except at the extremely wide ratios where deficiencies in one element were caused by excesses of others." And Reid (1996) conducted a study in the 1970s to determine the effects of lime and Ca:Mg ratios on alfalfa and birdsfoot trefoil and concluded that "ratios ranging from 267:1 to 1:1 had no significant influence on yields of either species" but that maintaining a pH at about 6.5 resulted in the highest yields. The general message from these studies is that adjustments to the Ca:Mg ratios per se do not affect crop yield except in extreme cases, but that the addition of Ca may improve yields if the soil pH is lower than the optimal range. All of the studies mentioned, however, approached the issue from a soil fertility point of view. Many proponents of cation balancing claim that the benefits of adding Ca are due to the long-term effects on soil structure which promote root growth and may subsequently affect N use efficiency and, perhaps, root diseases. This may in fact be the case in soils with poor structure - where N use efficiency is reduced because of poor root growth or because of denitrification from anaerobic pockets. But in soils with good structure I still don't see the logic in adding Ca. Ray mentioned that blossom end rot should be apparent on our tomatoes if there was a Ca deficiency in these soils. Again, this is a soil fertility/plant nutrition question rather than one of soil structure, but the answer is 'no' - we occasionally see some early season blossom end rot but it is not problem. He also mentioned checking the numbers again to make sure I had them right. Yes indeed they are. The soils throughout the western Sacramento Valley, I am told, are derived from marine deposits and Ca:Mg ratios are generally less than 1. Moreover the ground and surface waters used for irrigation have 2-3 times more dissolved Mg than Ca. Farmers do add gypsum if they have a water infiltration problem, but as I said, we certainly don't have one of those in the organic system. Based upon the research that has already been done I'm not so sure that it would be worth doing more studies in which Ca:Mg ratios are adjusted and yields measured. It seems enough have been done. Perhaps research focused just on soils with extremely low Ca:Mg ratios or on the reclamation of land with poor structure would be worthwhile. And as it stands now, I see little validity in the broad claims made by some consultants that the Ca:Mg ratio of an agricultural soil should be 6.5 to 1, even as a general rule. I am still interested in how this philosophical division between university and commercial laboratories occurred. It appears to have begun over a half century ago and it is amazing to me that it still exists. I am also still eager to hear from other "happy customers" about their own success stories from adding Ca (or unhappy customers) or from the consultants who recommend this practice. References cited Bear, F. E. and S. J. Toth. 1948. Influence of calcium on availability of other soil cations. Soil Sci. 65: 69-74. Eckert, D. J. and E. O. McLean. 1981. Basic cation saturation ratios as a basis for fertilizing and liming agronomic crops: I. Growth chamber studies. Agron. J. 73: 795-799. Liebhardt, W. C. 1981. The basic cation saturation ratio concept and lime and potassium recommendations on Delaware's Coastal Plain soils. Soil Sci. Soc. Am. J. 45: 544-549. Reid, W. S. 1996. Influence of lime and calcium:magnesium ratio on alfalfa and birdsfoot trefoil yields. Commun. Soil Sci. Plant Anal. 27: 1885-1900. M. Sean Clark Research Manager Sustainable Agriculture Farming Systems Project Department of Agronomy and Range Science University of California Davis, CA 95616 msclark@ucdavis.edu TEL:(916) 752-2023 FAX:(916) 752-4361 To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". From WILSONDO@phibred.com Wed Feb 18 21:04:26 1998 Date: Wed, 18 Feb 1998 15:20:19 -0600 From: "Wilson, Dale" To: sanet-mg@shasta.ces.ncsu.edu Subject: RE: Mg Ratios Bill, Thanks for shedding some light on this topic. This illustrates the importance of well-designed, long-term field research. Dale To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". From wcliebhardt@ucdavis.edu Wed Feb 18 21:04:40 1998 Date: Wed, 18 Feb 1998 11:29:55 -0800 From: Bill Liebhardt To: sanet-mg@shasta.ces.ncsu.edu Subject: Ca:Mg Ratios It has been interesting to see the dialog on this subject. I think I would like to provide some information that might help or maybe it will just muddy up the water. It will be somewhat my personal experience as a person trying to make sense of the science and art of soil testing over many years of work. In 1968 when I worked in the fertilizer industry I went to a training session and was first exposed to the philosophy of the cation balance between Ca, Mg, and K. It sounded OK to me and made some sense to have a balance in the soil. At that time I somewhat excepted it and went on with my work assuming that there was experimental evidence for this theory of dealing with soil testing. Later on at at the University of Delaware I set up an experiment that had zero, one and four tons of lime per acre using dolomitic lime, calcitic lime, and a mixture of the two in a factorial experiment with 0, 40 and 120 pounds per acre of potash. The experiment went for 11 years while I was there. In the later six or seven years of the experiment when the treatments were well established the data showed on sandy coastal plain soil with corn and soybeans that the philosophy of the Basic Cation Saturation Ratio did not operate with respect to yield. With the range of treatments that were in this experiment we had wide ranges of Ca and Mg saturation values as well as ratios. I did not set out to prove or disprove this philosophy at the start of the experiment but when I saw how this was being used particularly by the commercial soil testing establishment I saw a need to try to find out how this all got started. In the 70's and 80's many commercial labs were using this philosophy or the soil build up and maintenance philosophy or a combination of both which almost always resulted in fertilizer being added even when it was not needed. This was also true with some land grant soil testing labs. Many land grant labs used the sufficiency level approach which basically says you test for a nutrient and if lacking you apply that nutrient. A number of experiments were done in that time that compared fertilizer recommendations of labs with very different philosophies and invariably they showed the yields to be the same but the cost of the nutrients varied considerably, with the cation balance and soil build up and maintenance being more expensive by quite a bit. Good soil testing in my opinion is based on the idea that you have field data to support your nutrient recommendations. This means that you have done research with similar soils and crops so that when the farmers sample comes it can be compared to some research on similar soils and crops. That is the theory or basis of soil testing. There is much lacking in most states with regard to field calibration data and it is not a perfect world by any means. Now back to the cation balance story. When I began to see the data in my experiment I wanted to find out where this cation balance story started. After reading the trail first lead to people at Rutgers who had done an experiment. People there proposed the concept of the ideal soil that had certain amounts of CA, Mg and K. They took 20 soils from New Jersey and added various amounts of Ca, Mg, and K. They considered the ideal soil to have 65% CA, 10% Mg and 5% K. They found it very difficult to get the ratios they wanted. They dropped the idea I was told by people at Rutgers as not being practical. Another part of the story came from people at the University of Missouri-they used the cation balance theory in their soil testing program in early 80's when I was attempting to get to the bottom of this story. I called the soil testing lab at the University of Missouri and eventually after talking to a number of people was told to talk to a Dr. Grahm who was then retired. I called him and had a very pleasant conversation with him about the data I had in Delaware and asked him how the use of the cation balance came into use in Missouri. He said that he developed it for use on Missouri soils. I asked him how he developed this, what research did he have or information that I could cite or use. He then told me the story which I found to be very interesting. He said that he sat down at his desk after thinking about this for some time and came up with ratios that made sense to him based of the clay minerals in Missouri soils. He based this on his knowledge of Missouri soils and an article he had by a Dutch soil scientist by the name of Hissink. He said it was not based on field research but that it was he best estimate of how things out to be in Missouri. This then showed me that it was not based on hard data, research or evidence that I thought it should be. I have seen lots of fertilizer recommendations not based on good data but here was a philosophy being used all over the country and in my opinion it is a house of cards-it does not have a solid foundation that is research based. This is the story as I know it. There maybe other pieces out there that I do not know and I would like to hear or see the evidence that any one has to support this cation balance concept. If you have it you should come to the table with it. I know many people use the concept and say it works but I have yet to see any evidence that will stand up to review. It is somewhat amazing to me to see the basis for such concept be so lacking but yet go so far but I guess that is life. So my challenge to you supporters of this is to come forward with your information whatever it is and let all of us see it. If there is silence I will know the answer. Best Wishes to all, Bill *********************************************************** * * * Bill Liebhardt, Director SAREP * * 1 Shields Avenue * * University of California, Davis CA 95616 * * Phone: 530-752-2379 * * FAX: 530-754-8550 * * email: wcliebhardt@ucdavis.edu * * WWW: www.sarep.ucdavis.edu * * * *********************************************************** To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". From M.Turner@massey.ac.nz Wed Feb 18 21:04:55 1998 Date: Thu, 19 Feb 1998 13:04:14 +1300 From: Max Turner To: sanet-mg@shasta.ces.ncsu.edu Subject: Re: Ca:Mg Ratios At 11:29 AM 18/02/98 -0800, you wrote: >It has been interesting to see the dialog on this subject..... >In the 70's and 80's many commercial labs were using this philosophy or the >soil build up and maintenance philosophy or a combination of both which >almost always resulted in fertilizer being added even when it was not >needed. This was also true with some land grant soil testing labs. Many >land grant labs used the sufficiency level approach which basically says you >test for a nutrient and if lacking you apply that nutrient. Bill This business of SLAN versus BCSR is an area of special interest to me as I have been intimately involved in the development of a soil testing system in New Zealand and was forced to take a serious look at the pros and cons of the different methods. I favor the balance view, as a concept, even though I claim to be reasonably au fait with its dubious background. Let me elaborate. The question really is what happens if you DONT use balance as your basis? In my opinion the assessment of individual cations by the sufficiency approach can lead to problems of interactions between, for example, potassium and other essential cations, such as magnesium and sodium; particularly in grazed psture systems where the concern is as much for animal health as it is for simply plant yield. The argument I feel has unfortunately been one of EITHER the "sufficiency level" approach OR the "balanced cation ratios" approach, when really a combination is a much better solution. We have ample evidence of the troubles caused when only the SLAN is used on our grasslands and we therefore educate our students about the need to consider balance between cations. Hence the BCSR is an attractive concept. It points our fertiliser use in the right direction and forces a consideration of the whole complex of ions. We also, for the same reasons, embrace the Sumner DRIS method which attempts to take balance even further by providing a conceptual framework for incorporating soil and plant analysis. DRIS and BCSR have many common features. Neither have been thoroughly tested in this country, as yet Obviously bringing the animal into the equation is a new issue, but in the NZ situation we are often dealing with soil tests for pastures destined to be eaten by a grazing animal; so you cant leave the animal out. Approaching this with the notion of cation balance in the soil and in the plant does suggest we are cognisant of the interactions and implications of our fertilizer programs to all parts of the system. I find the SLAN methods rather sterile and not so integrative. The idea of studying each element in isolation is old science that has not really done much for animal welfare in this country. I should add however, that SLAN is still the basis on which many scientists and laboratories operate here; even in the grassland situation. I concur however that more research along these lines is needed. In our case, it is unlikely to eventuate as funding for soil testing research is a very low priority under current economic circumstances. You asked for feedback so I have obliged. I will be interested to hear what others contribute either for or against. Cheers Max Dr Max A. Turner Department of Soil Science Massey University Palmerstonn North NEW ZEALAND To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". From jgruv@wam.umd.edu Thu Feb 19 18:22:00 1998 Date: Thu, 19 Feb 1998 01:06:19 -0500 (EST) From: joel b gruver To: Bill Liebhardt Cc: sanet-mg@shasta.ces.ncsu.edu Subject: cation ratio thoughts Hello to all... After reading Bill Liebhardts interesting post I thought I would throw out a few additional ideas. As the use of relatively cheap fertilizers snowballed midway into this century, there must have been considerable desire among university agronomists to quickly develop systems by which they could scientifically recommend the use of fertilizer. My guess is that initally there was a real lack of data from fertilizer response field trials and so recommendation systems like cation balancing were hit upon as a quick way to make a "scientific" prediction of fertilizer need. As time progressed universities accumulated large amounts of field data and had a basis for switching over to "sufficiency" recommendations. So...without extensive field data and closer affiliation with fertilizer dealers, many private labs have stuck with cation balancing theories... makes sense to me... I would also suggest that it has taken considerably longer for field trial based rational recommendations for pesticides (i.e. IPM) to be in widespread use than for fertilizer. The biggest problem that I see with the current use of cation:balancing is that the recommended ratios are being touted as applicable to all soils. It seems to me that if the goal is to get the ideal ratio of Ca and Mg into a crop, it should be the ratio of Ca:Mg in the soil solution that is really the issue not the base saturation ratio on CE sites. Different soils have very different mineralogies and thus have different affinities for base cations. One base saturation ratio across many soils will lead to many to different ratios of cations in the soil solution. A quick search in the library tonight turned up an article that discusses this issue. Soil properties affecting the proportionate amounts of Ca, Mg and K in plants and in HCl extracts. Adolf Mehlich Soil Science Vol 62 pg 393. I believe the year was 1940. The article discusses cation ratios and is followed by a lit cited section that includes many other articles that appear to discuss cation ratio theories. I also observed that a number of articles including some by W.A. Albrecht investigated the effect of different base cation levels on amino acid levels and ratios in crops. There appeared to be evidence that amino acid synthesis in plants is effected by base cation levels in soil. With the vast breakthroughs in biochemistry that have occured since 1940 we must surely know more about base cation effects on crop protein quality than we did 50 years ago... right ??? What do we know ??? So in summary, as Bill L suggested, I think that soil test recommendations that are of consistent value must be derived from field trials... if optimal cation ratios for crop quality on particular soil types actually exist...lets figure this out using field trials... One set of cation ratios for the whole country defies basic scientific understanding of the variability of soil... Joel Gruver U of MD, Soil Quality research To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". From wcliebhardt@ucdavis.edu Sat Feb 21 00:31:54 1998 Date: Fri, 20 Feb 1998 12:11:58 -0800 From: Bill Liebhardt To: Max Turner Cc: sanet-mg@amani.ces.ncsu.edu Subject: Re: Ca:Mg Ratios At 01:04 PM 2/19/98 +1300, you wrote: >At 11:29 AM 18/02/98 -0800, you wrote: >>It has been interesting to see the dialog on this subject..... > >>In the 70's and 80's many commercial labs were using this philosophy or the >>soil build up and maintenance philosophy or a combination of both which >>almost always resulted in fertilizer being added even when it was not >>needed. This was also true with some land grant soil testing labs. Many >>land grant labs used the sufficiency level approach which basically says you >>test for a nutrient and if lacking you apply that nutrient. > >Bill > >This business of SLAN versus BCSR is an area of special interest to me as I >have been intimately involved in the development of a soil testing system in >New Zealand and was forced to take a serious look at the pros and cons of >the different methods. I favor the balance view, as a concept, even though I >claim to be reasonably au fait with its dubious background. Let me elaborate. > >The question really is what happens if you DONT use balance as your basis? >In my opinion the assessment of individual cations by the sufficiency >approach can lead to problems of interactions between, for example, >potassium and other essential cations, such as magnesium and sodium; >particularly in grazed psture systems where the concern is as much for >animal health as it is for simply plant yield. > >The argument I feel has unfortunately been one of EITHER the "sufficiency >level" approach OR the "balanced cation ratios" approach, when really a >combination is a much better solution. We have ample evidence of the >troubles caused when only the SLAN is used on our grasslands and we >therefore educate our students about the need to consider balance between >cations. Hence the BCSR is an attractive concept. It points our fertiliser >use in the right direction and forces a consideration of the whole complex >of ions. We also, for the same reasons, embrace the Sumner DRIS method which >attempts to take balance even further by providing a conceptual framework >for incorporating soil and plant analysis. DRIS and BCSR have many common >features. Neither have been thoroughly tested in this country, as yet > >Obviously bringing the animal into the equation is a new issue, but in the >NZ situation we are often dealing with soil tests for pastures destined to >be eaten by a grazing animal; so you cant leave the animal out. Approaching >this with the notion of cation balance in the soil and in the plant does >suggest we are cognisant of the interactions and implications of our >fertilizer programs to all parts of the system. MAX, I THINK YOU RAISE SOME VERY INTERESTING AND VALID POINTS. I ALSO THINK THERE ARE MANY WAYS OF KNOWING RATHER THAN JUST VIA REPLICATED EXPERIMENTS. THE VALUE OF BALANCE MAYBE IMPORTANT AND YOUR ANIMAL SYSTEMS MAYBE AN EXAMPLE. WHAT I HAVE SEEN WITH THE BSCR CONCEPT HERE IS THAT THERE IS NO RESEARCH OR INFORMATION PUBLISHED THAT SUPPORTS USING THIS APPROACH. I THINK THE IDEA HAS MERIT BUT IT NEEDS SOME INFORMATION TO SHOW THAT IT REALLY HELPS FORMULATE GOOD NUTRIENT MANAGEMENT. THE RESEARCH WE HAVE TO DATE DOES NOT SUPPORT THAT. GOOD FIELD CALIBRATION DATA OR RESEARCH MEANS THAT YOU HAVE DATA TO BACK UP YOUR NUTRIENT RECOMMENDATIONS. IT IS IN MY OPINION LIKE THE STANDARD CURVE WE DEVELOP FOR ANY CHEMICAL ANALYSIS. SUPPOSE YOU WENT TO THE DR. FOR AN ANALYSIS OF YOUR BLOOD GLUCOSE AND THE LAB DID NOT HAVE A STANDARD CURVE FOR GLUCOSE. YOU WOULD HAVE A NUMBER BUT IT WOULD BE MEANINGLESS-IT IS NUMBER BUT NOTHING BEHIND IT. IN MY OPINION THAT MAYBE WORSE THAN NOTHING. I HAVE SEEN FARMERS WITH A SOIL TEST HAVE A PH OF 6.5 WITH BSCR METHOD BEING ADVISED TO PUT ON CALCIUM SULFATE BECAUSE IT DID NOT HAVE THE SO CALLED CORRECT RATIO WHEN LOCAL FIELD CALIBRATION DATA SHOWED THAT IT WAS NOT NECESSARY IF CROP YIELD AND PROFIT IS A CRITERIA. IT IS THE ABUSE OF PROPER PROCESS THAT IRRITATES ME AND MANY OTHERS IN THIS FIELD. IF YOU CAN COME UP WITH GOOD NUTRIENT MANAGEMENT WITH BCRS AND DRIS OR WHATEVER CONCEPT AND YOU HAVE RESEARCH AND DATA TO SHOW IT WORKS AND IS REASONABLE AND IT IS NOT JUST NUMBER PULLED OUT OF THE AIR THEN THAT IS FINE. YOU HAVE FOLLOWED A PROCESS THAT IS INTELLECTUALLY AND OPERATIONALLY HONEST AND NOT DECEPTIVE. THAT IN MY OPINION IS WHAT WE SHOULD STRIVE FOR. IF A FARMER QUESTIONS YOU AS TO WHY YOU ARE DOING IT ONE WAY OR ANOTHER AND YOU HAVE INFO TO SAY WE DID IT THIS WAY BECAUSE WE HAVE RESEARCH OR DATA TO BACK UP WHAT WE SAY. THE SLAN METHOD MAYBE STERILE BUT IT HAS SOMETHING BEHIND IT IN THE US. IT RESULTS IN ECONOMICALLY, AGRONOMIC ALLY AND ENVIRONMENTALLY SUPERIOR NUTRIENT MANAGEMENT IN THE US. THERE IS MUCH RESEARCH TO SHOW THAT. I THINK THAT GOOD SOIL ORGANIC MATTER MANAGEMENT OUT TO BE THE BASIS OF A HOLISTIC WAY OF MANAGING OUR SOILS. WE CAN DO MORE TO HELP OUR SOILS BY LOOKING AT THIS ASPECT THAN ALMOST ANYTHING WE DO. THERE IS RESEARCH THAT SHOWS THAT FARMING SYSTEMS THAT DO A GOOD JOB IN THIS AREA SOLVE SO MANY OF THE OTHER PROBLEMS ASSOCIATED WITH FARMING. > >I find the SLAN methods rather sterile and not so integrative. The idea of >studying each element in isolation is old science that has not really done >much for animal welfare in this country. I should add however, that SLAN is >still the basis on which many scientists and laboratories operate here; even >in the grassland situation. > >I concur however that more research along these lines is needed. In our >case, it is unlikely to eventuate as funding for soil testing research is a >very low priority under current economic circumstances. DEVELOPING FIELD CALIBRATION DATA IN THE US IS NOT WHAT IS SHOULD BE BY ANY MEANS. IT DID AND DOES NOT RANK HIGH WITH THE PROMOTION PROCESS IN MANY INSTITUTIONS. IT IS NOT FUNDED WELL HERE ALSO. IT HAS NOT GOT THE PIZZAZZ THAT SOME AREAS OF ENDEAVOR HAVE. WE ALSO HAVE NOT DONE A GOOD JOB OF COMMUNICATION WITH THE PUBLIC OR FARMERS ON THIS. I RECENTLY TALKED TO A FARMER WHO PLOWED DOWN ALFALFA, PUT ON LOTS OF LIQUID MANURE AND APPLIED 250 POUNDS OF N AS FERTILIZER TO GROW SILAGE CORN. HE PROBABLY HAD 600-700 POUNDS OF N PER ACRE. WHEN I ASKED HIM WHY HE USED FERTILIZER N HE SAID HE WAS ADVISED BY HIS AG CHEM DEALER. THE ALFALFA AND MANURE COUNTED FOR NOTHING. WE HAVE A LONG WAY TO GO FOR SURE. BILL LIEBHARDT > >You asked for feedback so I have obliged. I will be interested to hear what >others contribute either for or against. > >Cheers > >Max > > >Dr Max A. Turner >Department of Soil Science >Massey University >Palmerstonn North >NEW ZEALAND > > >To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". >To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command >"subscribe sanet-mg-digest". > > *********************************************************** * * * Bill Liebhardt, Director SAREP * * 1 Shields Avenue * * University of California, Davis CA 95616 * * Phone: 530-752-2379 * * FAX: 530-754-8550 * * email: wcliebhardt@ucdavis.edu * * WWW: www.sarep.ucdavis.edu * * * *********************************************************** To Unsubscribe: Email majordomo@ces.ncsu.edu with "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest".