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Wheat Fallow Tillage Systems' Effect on a Newly Cultivated Grassland Soils' Nitrogen Budget
Author(s) -
Lamb J. A.,
Peterson G. A.,
Fenster C. R.
Publication year - 1985
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1985.03615995004900020016x
Subject(s) - agronomy , tillage , mulch , plough , loam , leaching (pedology) , environmental science , grassland , soil water , crop rotation , crop , biology , soil science
The objective of this study was to examine soil nitrogen (N) losses from grassland soil as affected by time since the beginning of cultivation. A native grassland site was cultivated for winter wheat ( Triticum aestivum L.) production in a crop‐fallow rotation under three tillage systems; no‐till, stubble mulch, and plow (bare fallow). The experiment was located in Western Nebraska on a Duroc loam (fine silty, mixed, mesic, Pachic Haplustolls). After 12 yr of cultivation, losses of soil N from the 0 to 30 cm depth were 3% for no‐till, 8% for stubble mulch, and 19% for the plow tillages. Potential loss by erosion was small because of protection from wind by the surrounding grasslands. These results suggest decreased stirring of the soil resulted in major N savings beyond erosion losses. The sum of NO − 3 ‐N greater than that found below the sod control plus crop removal of N accounted for essentially all of the soil N lost from stubble mulch and plow tillages. In the no‐till environment, crop removal of N and leached NO − 3 ‐N accounted for more N than had been lost from the soil since cultivation began. Plow tillage system resulted in leaching of 100 kg ha −1 more NO − 3 ‐N than occurred with no‐till or stubble mulch. Soil N in the 0‐to 30‐cm soil depth was fractionated into exchangeable NH + 4 ‐N, nonexchangeable NH + 4 ‐N, and nonhydrolyzable N. The nonexchangeable and exchangeable NH + 4 ‐N fractions were not affected by cultivation. The nonhydrolyzable N fraction was reduced by all forms of tillage and accounted for a substantial part of the soil N losses.