Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2001
Publication Date: 12/1/2001
Citation: WIENHOLD, B.J., TANAKA, D.L. SOIL PROPERTY CHANGES OCCURRING DURING CONVERSION OF A CRP SITE TO ANNUAL CROPPING. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 65:1795-1803. 2001. Interpretive Summary: A study was conducted to assess how common farming practices affect soil properties on Conservation Reserve Land (CRP) being returned to crop production. The objective was to identify practices that would maintain gains made in soil and water conservation while the land was in CRP. Soil properties were measured in 1995 and 1997. Soil properties in reference areas, areas maintained in CRP vegetation, did not change from 1995 to 1997 suggesting that soil conditions had reached an equilibrium. Haying, and tillage affected a number of soil properties. In hayed plots, the response of most soil properties to tillage and N fertilization was similar to that observed in many long- term cropping studies in the region. Non-hayed plots did not respond in a predictable manner, likely the result of continued decomposition of the large amount of residue present. Predictable soil responses are necessary for implementing management practices. Our results suggest that haying and use of conservation tillage and annual cropping practices developed for this region would effectively convert CRP land to crop production while maintaining gains made in soil and water conservation. These results will be useful to producers and action agencies involved in management decisions regarding post- contract use of land in CRP.
Technical Abstract: Management practices for conversion of land enrolled in the Conservation Reserve Program (CRP) to crop production are needed. Effect of haying (hayed or not hayed), tillage (no-tillage, minimum tillage, and conventional tillage), and N fertilization (0 or 67 kg ha-1) on soil physical, chemical, and biological properties were assessed in 1995 and 1997 at a CRP site in North Dakota having Amor loam (Fine-loamy, mixed, superactive, frigid, Typic Haplustoll) and Cabba silt loam (Loamy, mixed, superactive, calcareous, frigid, shallow, Typic Haplustoll) soils in a spring wheat (Triticum aestivum L.), winter wheat, pea (Pisum sativum L.) rotation. Reference areas maintained with perennial vegetation were included. Soil physical properties measured were not altered sufficiently to impact crop growth. Ammonium content decreased from 1995 (4.6 kg ha-1) to 1997 (0.9 kg ha-1). Nitrate content was similar among treatments in 1995 and in non-hayed plots in 1997, while in hayed plots NO3-N increased as tillage intensity decreased. Organic C and total N content declined (1.2 Mg ha-1 for C and 0.1 Mg ha-1 for N) from 1995 to 1997. In hayed plots organic C and total N increased as tillage intensity decreased while in non-hayed plots no pattern was observed. Potentially mineralizable N at 0 to 5 cm increased as tillage intensity decreased in 1997. In the 5 to 15 cm depth, potentially mineralizable N increased from 1995 (118 kg ha-1) to 1997 (146 kg ha-1). By 1997 soil properties in hayed plots responded to tillage and N fertilization similarly to those in established cropping systems in the region.