Cover Crop Absorption and Deep Leeching Reductions of Soil N in Corn Agroecosystems

Kavdir, Y. and A.J.M. Smucker

Presented at the All Scientist Meeting (1999-07-20 to 1999-07-21 )

Alfalfa increased mineral soil N by decreasing leaching losses of fixed plant and residual soil nitrogen (Rasse and Smucker, 1999). Soil and plant nitrogen pools were studied under rye cover cropping of a Kalamazoo loam soil (mixed, mesic Typic Hapludalf) from 1997 to 1999 under four regimes of soil and plant residues: 1) bare fallow soil (F), 2) bare fallow soil with rye shoot mulch applied in May (FS), 3) bare soil with rye roots (shoots removed) in May (RR), and 4) rye cover with rye roots and shoot mulch applied to the soil surface in May (RRS). Extractable soil N was maximum in April 1998 in F treatments. RR treatments delayed maximum accumulations of soil N until August 1998. Rye cover crops decreased soil N by nearly 160 kg N ha-1during the wet periods from December 1997 to April 1998. Much of this N was absorbed by the rye cover. Rye cover retained more of the remaining soil N in the upper soil horizons within reach of roots by the successive corn crop. After spring killing of the rye cover, soil extractable N contents increased 150 kg N ha-1, from 192 to 342 kg N ha-1. These results suggest that roots of winter rye cover sequester soil N and reduce deep leaching of soluble soil N when compared to bare fallow soil. This timely sequestered and slow-release soil N can be used by succeeding corn plants reducing fertilizer costs and NO3 leaching from the soil profile.

Alfalfa increased mineral soil N by decreasing leaching losses of fixed plant and residual soil nitrogen (Rasse and Smucker, 1999). Soil and plant nitrogen pools were studied under rye cover cropping of a Kalamazoo loam soil (mixed, mesic Typic Hapludalf) from 1997 to 1999 under four regimes of soil and plant residues: 1) bare fallow soil (F), 2) bare fallow soil with rye shoot mulch applied in May (FS), 3) bare soil with rye roots (shoots removed) in May (RR), and 4) rye cover with rye roots and shoot mulch applied to the soil surface in May (RRS). Extractable soil N was maximum in April 1998 in F treatments. RR treatments delayed maximum accumulations of soil N until August 1998. Rye cover crops decreased soil N by nearly 160 kg N ha-1during the wet periods from December 1997 to April 1998. Much of this N was absorbed by the rye cover. Rye cover retained more of the remaining soil N in the upper soil horizons within reach of roots by the successive corn crop. After spring killing of the rye cover, soil extractable N contents increased 150 kg N ha-1, from 192 to 342 kg N ha-1. These results suggest that roots of winter rye cover sequester soil N and reduce deep leaching of soluble soil N when compared to bare fallow soil. This timely sequestered and slow-release soil N can be used by succeeding corn plants reducing fertilizer costs and NO3 leaching from the soil profile.Figures 1 and 2

Back to meeting | Show |
Sign In