Browse on keywords: crop rotation ID organic matter
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2928. Idaho Agr. Expt. Sta.. 1949. Annual report.. ID Agr. Expt. Sta. Bull. #276.
Sweetclover maintained OM levels, slight loss in W-P; N fertilizer reduced OM losses where straw was removed.
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.
10235. Collins, H.P., P.E. Rasmussen, and C.L. Douglas Jr.. 1992. Crop rotation and residue management effects on soil carbon and microbial dynamics.. Soil Sci. Soc. Amer. J. 56:in press.
Total soil and microbial biomass C and N contents were significantly greater in annual crop than wheat-fallow rotations, except when manure was applied. Microbial biomass C in annual crop and wheat-fallow rotations averaged 50 and 25%, repsectively, of that in grass pasture. Residue management significantly influenced the level of microbial biomass C; for example, burning residues reduced microbial biomass to 57% of that in plots receiving manure. Both microbial counts and microbial biomass were higher in early spring than other seasons. Annual cropping significantly reduced declines in soil organic matter and microbial biomass.
10256. Mallawatantri, A.P.. 1990. Effects of long-term management, slope position, and depth on pesticide transport parameters.. manuscript, Dept. of Crops & Soils, Washington State University, Pullman..
Pesticide adsoprtion was compared on soils from adjacent farms, with one farm using a low-input system and the other a conventional system. Adsorption of pesticide by soil is signficantly controlled by the organic carbon content of the soil. Carbon content was higher on the low-input farm, and also varied with landscape position on both farms. The relative adsorption of the four pesticides studed was diuron > metribuzin, triallate > 2,4-D. Adsorption was higher on the low-input farm, at bottom slope positions with higher soil carbon, and in surface soils than in subsoils. Weakly adsorbed pesticides should be avoided on top slope and eroded areas due to increased risk of movement. The green manure rotation on the low-input farm reduced potential pesticide transport due to higher soil carbon levels.