Spring Wheat Straw Production and Composition as Influenced by Topsoil Removal

Wind and water erosion have resulted in reduced crop productivity and created soil management problems. Management of crop residues can be effective for soil erosion control, but influences of soil erosion on crop residue production is unknown. The purpose of this study was to determine total residue production and residue N and P concentration and content for 8 yr as influenced by topsoil removal and additions of N and P fertilizer for a spring wheat ( Triticum aestivum L.)‐fallow system. Total straw production for the first increment of P increased ≈ 14% for 0.00‐ and 0.06‐m soil removal treatments compared with ≈ 33% for 0.12‐ and 0.18‐m soil removal treatments. Total straw production was increased more than total grain production with the addition of N and P fertilizer. Total straw production for 0.12‐ and 0.18‐m soil removal treatments needed at least 20 kg P ha −1 and 35 kg N ha −1 to equal or exceed that for 0.00‐m soil removal treatment with no fertilizer additions. Total straw N content decreased 33% as soil removal increased from 0.00 to 0.18 m. While total straw P content was considerably less than total straw N content, both decreased about 32% for 0.18 m compared with 0.00‐m soil removal treatments. Greater total straw N and P content for the 0.00‐m soil removal treatment was due to greater total straw production as well as greater N and P concentrations. Consequently, cycling of N and P may be reduced for eroded soils due to low quantities of residue as well as low N and P concentrations in the residues.