From sgroff@epix.net Mon Mar 29 13:47:00 1999 Date: Sun, 28 Mar 1999 22:14:56 -0500 From: Steve Groff To: sanet Subject: soil discoveries Sanet, We are putting in 3,400 ft of underground irrigation lines and it has been fascinating to see what the soil profile looks like across several different fields. Joel Gruver (U of MD) and his assistant were here yesterday collecting a 3 ft profile of soil from the sidewall if the trench. They pointed out earthworm channels that extended below the bottom of the trench and showed me the roots that followed the channels. All my fields are cover cropped and I was amazed at the living roots of the 5" tall rye that were noticed 3 ft below the soil surface! It reinforced to me the importance of keeping the soil covered and to always have something growing in a field. Steve Groff -- "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 the command "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail From WILSONDO@phibred.com Mon Mar 29 13:47:24 1999 Date: Mon, 29 Mar 1999 09:35:37 -0600 From: "Wilson, Dale" To: sanet Subject: RE: soil discoveries [ 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. ] Steve and Joel, > We are putting in 3,400 ft of underground irrigation lines > and it has been fascinating to see what the soil profile > looks like across several different fields. Steve, your post, and the compost I was shoveling on Saturday reminded me of a question on the soil/plant relationship I have wondered about for a long time: What is the effect and value to the plant from (sub-meter) spatial heterogeneity in the soil? The compost I was using was mainly 1997 oak leaves. The leaves were packed and mostly dark and friable, interlaced with fungi and roots, with a deep mushroom odor. Along with the leaf mold were sticks up to an inch in diameter in various stages of decay. I put a large amount (about 10 bu on 150 square feet) because the bed really needed lightening up. I did my best to mix the compost in, but the soil is very heterogenous now. As roots explore this, they are going to find many diverse microenvironments. Aside from the difficulty of getting a good seedbed in this, I imagine this heterogeneity is good for plants. Even if the net characteristics of the soil would reduce availability of certain nutrients, the spatial/chemical diversity of the medium will insure that some part of the root system can find whatever the plant needs. This is why banded fertilizer application is so successful at getting P into the plant even under conditions conducive to P fixation. Roots grow into the region of nutrient availability. Perhaps one of the values of no-till is stratification of the profile into chemically distinct zones. Beneficial effect of heterogeneity could also be a rationale for incorporation of raw organic matter in minimum-till systems (a little like my garden bed). Zones of decaying residue might provide a more complete smorgasbord for plants. Other situations where spatial heterogeneity might be important include places where the subsoil has anion-exchange capacity, and under drip-irrigation. I found a few relevant abstracts I'll send you two personally (if anyone else wants them, let me know). Dale To Unsubscribe: Email majordomo@ces.ncsu.edu with the command "unsubscribe sanet-mg". To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command "subscribe sanet-mg-digest". All messages to sanet-mg are archived at: http://www.sare.org/san/htdocs/hypermail