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United States Department of Agriculture

Agricultural Research Service

Title: Effects of Cultural Practices on Nitrate in Soil and Nitrogen in Grain Sorghum

Authors
item Sow, A - TEXAS A&M UNIVERSITY
item Hossner, L - TEXAS A&M UNIVERSITY
item Unger, Paul
item Stewart, B - WEST TEXAS A&M UNIVERSITY

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 1997
Publication Date: N/A

Interpretive Summary: Methods of managing crop residues affect soil conditions in many ways. In this study, we examined the effects of tillage and residue management on soil nitrate content, N content of plant tissues, and yields of dryland grain sorghum grown on Pullman clay loam at Bushland, Texas. Treatments were conventional (sweep) tillage plus furrow diking (FD), conventional tillage (CT), no-tillage with wheat residues maintained on the surface (NT+), and no-tillage with the residues removed (NT-). The FD and NT+ treatment plots had more plant available soil water than other treatment plots during most of the growing season. The differences were greatest at flowering and at harvest. At the half-bloom stage, soil nitrate was greater with FD than with other treatments at the 30- to 60-cm depth. At the 0- to 7.5-cm depth, nitrate differences due to FD, CT, and NT+ treatments were not significant. The N content of sorghum leaves, stover, and grain was greater with FD than with other treatments. Plant available soil water content, soil nitrate content, sorghum leaf N content, and grain and stover yields were affected by the tillage and residue management practices. Soil water use was greatest at the 0- to 1.2-m depth, but some water use also occurred at the 1.2- to 1.8-m depth. In the semiarid environment of the southern Great Plains, the FD and NT+ treatments were more suitable than the CT and NT- treatments for dryland grain sorghum production in a wheat-sorghum-fallow cropping systems for which all crop are grown on unfertilized fields.

Technical Abstract: Crop residue management influences the soil physical, chemical, and biological environment. Our objective was to examine tillage and residue management effects on soil nitrate, N in plant tissue, and yields of rainfed grain sorghum [Sorghum bicolor (L.) Moench]. Field experiments conducted on Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll) included conventional tillage plus furrow diking (FD), conventional tillag (CT), no-tillage with wheat (Triticum aestivum) residue maintained on the plots (NT+) and no-tillage with residue removed (NT-). Soil water was monitored throughout the growing season. Furrow diking and NT+ treatments had greater available soil water during most of the growing season with the greatest differences at flowering and at harvest. Furrow diking resulted in greater (P < 0.05) soil NO3-N at the 30- to 60-cm depth at half bloom. No significant differences for soil NO3-N were observed at the 0- to 7.5-cm mdepth in FD, CT, and NT+ plots. Concentrations of N in leaf, stover, and grain were greater in plants with FD than with other treatments. Available soil water, soil NO3-N, sorghum leaf composition, and grain and stover yields were noticeably responsive to tillage and wheat residue management. Available soil water was more depleted in the 0- to 1.2-m depth than at greater depths but the data also indicated that grain sorghum removed water from 1.2- to 1.8-m depths. In the semi-arid environment of the U.S. southern Great Plains either the FD or the NT+ treatments was most suitable for grain sorghum production in a wheat-sorghum-fallow (WSF) system where all the crops are grown on unfertilized fields.

Last Modified: 9/10/2014
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