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Organic & Integrated Tree Fruit Production

Saturday, July 21, 2018

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1172. Campbell, C.A., K. Bowren, G. LaFond, H. Janzen, and R.P. Zentner. 1989. Effect of crop rotations on soi organic matter in two black chernozems.. Soil and Crop Workshop, Univ. Saskatchewan, Saskatoon, Feb. 1989.

2735. Horner, G.M., M.M. Oveson, G.O. Baker, and W.W. Pawson.. 1960. Effect of cropping practices on yield, soil organic matter and erosion in the Pacific Northwest wheat region.. PNW Technical bulletin 1; USDA-ARS and Ag. Expt. Sta.'s of ID, OR, WA.
Summary of soil management experiments conducted over 40 yrs at six experiment stations. Covers: crop rotation, fertilization, and use of organic material. Some results: sweetclover and alfalfa were more effective than other legumes in increasing wheat yield. Yields of wheat were markedly affected by the sequences of cropping. Return of straw to soil decreased yields slightly under low N conditions. Organic and mineral N had no effect on yields in low precip. zones. Also covers runoff and erosion. T: many, eg.: effect of crop rotations on crop yield; crop yield as affected by grass/clover; effect of OM on wheat yield.

2995. Jacklin, A.W.. 1936. Crop rotations.. USDA-SCS Agronomy - Range Meetings, Pullman, WA #580.
Use legume grass mix in higher rainfall area, grasses in drier areas; rotations are typically 4-7 yr long; perennials can help check the weed problem; subsoiling effect of alfalfa, sweetclover reduces erosion and run-off; grass roots superior in soil aggregation.

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.

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.

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