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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #202257
Title: Nitrogen storage with cover crops and nitrogen fertilization in tilled and non-tilled soils

Author
item Sainju, Upendra
item SINGH, BHARAT - FORT VALLEY STATE UNIV

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2007
Publication Date: 5/6/2008
Citation: Sainju, U.M., Singh, B.P. 2008. Nitrogen conservation with cover crops and nitrogen fertilization in tilled and non-tilled soils. Agronomy Journal. 100:619-627.

Interpretive Summary: Increase in the cost of nitrogen (N) fertilization due to consistent increase in the price of petroleum for sustainable crop production is a growing concern. Higher rate of N fertilization to increase crop yields not only increases the potential for N leaching but also reduces its efficacy. Therefore, improved soil and crop management practices are needed to increase N cycling and N conservation so that the rate and cost of N fertilization and the potential for N leaching can be reduced. An experiment was conducted to examine the effects of four cover crops {legume (hairy vetch), nonlegume (rye), biculture of legume and nonlegume (vetch + rye), and no cover crops (or winter weeds)] and three N fertilization rates (0, 60 to 65, and 120 to 130 kg N ha-1) on crop reside N input and soil total N content in tilled and non-tilled soils from 2000 to 2002 in central Georgia. Nitrogen inputs were greater in vetch and vetch + rye with N rates than in rye and weeds with or without N rates, regardless of tillage. Soil total N content at the 0 to 90 cm depth was greater in vetch and vetch + rye with N rates than in weeds with or without N rates in no-tilled and chisel-tilled soils and at 0 to 30 cm was greater with vetch and vetch + rye than with weeds in strip-tilled soils. As a result, soil N at 0 to 30 cm can be can be conserved at 71 to 108 kg N ha-1 yr-1 with vetch and vetch + rye compared with a loss at 48 to 110 kg N ha-1 yr-1 with weeds, regardless of N rates and tillage. Because of similar soil N levels between vetch and vetch + rye and between 60 to 65 and 120 to 130 kg N ha-1, vetch can be replaced by vetch + rye and N fertilization rates can be reduced by half to maintain soil N level and reduce the cost of N fertilization and the potential for N leaching. These management practices can be used to conserve soil N, increase N-use efficiency and reduce N leaching while maintaining crop production in the areas where cover crops can be grown in the winter and potentials for N leaching is high, regardless of tillage practices.

Technical Abstract: Higher cost of nitrogen (N) fertilization due to increase in the price of gasoline and increased N leaching from croplands necessitate that soil N be conserved and N fertilization rate be reduced. Proper crop and N management practices may increase soil N conservation and reduce N fertilization rate. We examined the influence of four cover crops {legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secaele cereale L.)], biculture of legume and nonlegume (vetch + rye), and no cover crops (or winter weeds)} and three N fertilization rates [0, 60 to 65, and 120 to 130 kg N ha-1 (0, 54 to 58, and 108 to 116 lb N ac-1)] on N inputs from cover crops, cotton (Gossypium hirsutum L.), and sorghum [Sorghum bicolor (L.) Moench)] and soil total N (STN) content in tilled and non-tilled soils from 2000 to 2002 in central Georgia. Nitrogen inputs were greater in vetch and vetch + rye with N rates than in rye and weeds with or without N rates, regardless of tillage. The STN concentration decreased with depth and varied with date of sampling. The STN content at the 0 to 90 cm (0 to 36 in) depth was greater in vetch and vetch + rye with N rates than in weeds with or without N rates in no-tilled and chisel-tilled soils and at 0 to 30 cm (0 to 12 in) was greater with vetch and vetch + rye than with weeds in strip-tilled soils. As a result, soil N at 0 to 30 cm (0 to 12 in) can be can be conserved at 71 to 108 kg N ha-1 yr-1 (63 to 96 lb N ac-1 yr-1) with vetch and vetch + rye compared with a loss at 48 to 110 kg N ha-1 yr-1 (43 to 86 lb N ac-1 yr-1) with weeds, regardless of N rates and tillage. Because of similar STN levels between vetch and vetch + rye and between 60 to 65 and 120 to 130 kg N ha-1 (54 to 58 and 108 to 116 lb N ac-1), vetch can be replaced by vetch + rye and N fertilization rate can be reduced to maintain soil N level and reduce the cost of N fertilization and the potential for N leaching.