Browse on keywords: crop rotation soil quality organic matter
Search results on 06/18/18
2406. Hanley, Paul (ed.). 1980. Earthcare: Ecological agriculture in Saskatchewan.. Earthcare Information Centre.
A well-written text covering all aspects of biological farming in the prairie region of Saskatchewan. Practices apply to small and large farms. Includes reports from selected farms. References at the end of chapters.
3107. Dormaar, J.F. and C.W. Lindwall. 1989. Chemical differences in dark brown chernozemic Ap horizons under various conservation tillage systems.. Can. J. Soil Sci. 69:481-488.
Soil properties were investigated in two long-term studies: a 19 yr study of till vs. no-till in wheat fallow, and a 9 yr study of till vs. no-till with 3 rotations, including continuous cropping. No-till had the predominant influence on improving various soil physical and microbial properties. There was little difference in continuous cropping versus wheat-fallow, with tillage. The study compared soil from the entire plow depth, and concluded that 19 yr was long enough for the entire Ap horizon to benefit from no-till. No-till in both studies led to 40% of the dry aggregates being >0.84 mm. Dehydrogenase and phosphatase activities were twice as high under no-till as under cultivatiion. No-till also led to the largest monosaccharide accumulation in the soil.
5771. Reganold, J.P., L.F. Elliott and Y.L. Unger. 1987. Long-term effects of organic and conventional farming on soil erosion.. Nature, 330(26 Nov.):370-372.
The long-term effects (since 1948) of organic and conventional farming on selected properties of the same soil are compared. The organically-farmed soil had significantly higher organic matter content, thicker topsoil depth, higher polysaccharide content, lower modulus of rupture and less soil erosion than the conventionally-farmed soil. This study indicates that, in the long term, the organic farming system was more effective than the conventional farming system in reducing soil erosion and, therefore, in maintaining soil productivity. T: Mean values of conventional and organic farm soil properties.
5761. Reganold, J.P.. 1988. Comparison of soil properties as influenced by organic and conventional farming systems.. Am. J. Alt. Agric., 3(4):144-155.
This paper summarizes data from previous and current studies on two adjacent farms, one organically managed and the other conventionally managed, in the Palouse region of eastern Washington. The 320-hectare organic farm has been managed without the use of commercial fertilizers and only limited use of pesticides since the farm was first plowed in 1909. The 525-hectare conventional farm, first cultivated in 1908, began receiving recommended rates of commercial fertilizers and pesticides in 1948 and the early 1950's, respectively. The organically-farmed Naff silt loam soil had significantly higher organic matter, cation exchange capacity, total nitrogen, extractable potassium, water content, pH, polysaccharide content, enzyme levels, and microbial biomass than did the conventionally-farmed Naff soil. Also, the organically-farmed soil had significantly lower modulus of rupture, more granular structure, less hard and more friable consistence, and 16 centimeters more topsoil. This topsoil difference between farms was attributed to significantly greater erosion on the conventionally-farmed soil between 1948 and 1985. The difference in erosion rates between farms was most probably due to their different crop rotation systems; i.e., only the organic farm included a green manure crop in its rotation, and it had different tillage practices. These studies indicate that, in the long-term, the organic farming system was more effective than the conventional farming system in maintaining the tilth and productivity of the Naff soil and in reducing its loss to erosion.
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.