Browse on keywords: crop rotation ID nitrogen
Search results on 03/23/19
2249. Granatstein, D., D. Bezdicek, L. Elliott, V. Cochran, and J. Hammel. 1987. Long-term tillage and rotation effects on soil microbial biomass, carbon, and nitrogen.. Biol. Fertil. Soils 5:265-270..
This research examined plots that had been under different tillage and rotational management for 12 years. Rotations were WP (winter wheat-spring pea); WBP (winter wheat-spring barley-spring pea); WPA (winter wheat-spring pea undersown with red clover and alfalfa)-clover/alfalfa GM). The two tillages studied were moldboard plowing and no-till. There was little difference in microbial biomass, C or N below 5 cm in the no-till, with surface values being highest. Few differences due to rotation could be detected. The WPA rotation had the highest total C and N. Microbial biomass was higher in no-till surface soils where the preceding crop had provided high residue, while the opposite was true for tilled plots. Microbial biomass levels changed little from April to September, and then jumped higher in October with the advent of moisture.
3955. Mahler, R.L. and D.L. Auld. 1989. Evaluation of the green manure potential of Austrian winter peas in northern Idaho.. Agron. J. 81:258-264.
Austrian winter peas were evaluated as a green manure (GM) or seed pea (SP) crop, along with soil N levels, and subsequent yields of winter wheat (WW) and spring barley (SB). Four rotations were tested: GM-WW-SB; SP-WW-SB; SB-WW-SP; SF-WW-SB. Average N fertilizer equivalent values of 94, 75, and 68 kg/ha were provided by GM, SP, and SF (fallow) respectively, to the following wheat crop. Yield differences due to crop rotation or N fertilization rate were not observed in the third year of the cropping sequence. Austrian winter peas used as either a GM or SP provided more inorganic N than SF or SB. Although cereal crop yields were comparable, the SP-WW-SB was more profitable than GM-WW-SB or SF-WW-SB, due to the extra harvested crop.
7242. Veseth, R.. 1989. Reduced tillage for green manure legumes. STEEP Conservation Farming Update, Summer 1989, p. 3-5.
Three tillages were compared for incorporating Austrian winter pea or red clover green manure: moldboard plow plus shallow disk; shallow disk twice; no-till. At each N fertilizer rate, winter wheat yields were slightly higher with reduced tillage than with conventional tillage. A 60 lb/ac N rate substantially increased wheat yields after green manure, while the 120 N rate gave little or no yield increase. With no N fertilizer, the yield of winter wheat after both green manure crops compared favorably with yield of no-till winter wheat after a seed crop of spring peas. Legume N uptake by a following wheat crop was not affected by residue treatment, but recovery of legume N from the soil was about 10% lower with surface application than with soil incorporation. Also, wheat yields after chemically-killed green manures were consistently lower, and could not be fully recovered with fertilizer N. The mechanism of this suppression is not known.