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1015. Bowren, K.E. (ed.).. 1986. Soil improvement with legumes.. Saskatchewan Agriculture, Soils and Crops Branch.
This excellent publication summarizes research over the past 40 years pertaining to the use of legumes for soil improvement in Saskatchewan. The role of legumes in maintaining soil nitrogen was crucial prior to available fertilizer. But their value extends beyond their nitrogen contribution to the improvement of soil physical properties. One study found the tillage draft requirement to be up to one-third lower where legumes had been a regular part of the rotation. The positive effects of alfalfa were measured for over ten years in a series of wheat crops compared to plots with no alfalfa. Over 17 years, the average grain yield from a wheat-wheat/clover-clover green manure rotation with no fertilizer were 30% higher that a wheat-wheat-fallow rotation with fertilizer. Moisture depletion by legumes is the biggest hurdle to their use in very dry areas. Adequate fertility for the legumes is necessary to maximize their benefit. Use of selected Rhizobium strains can improve nitrogen fixation, especially on acid soils. Several varieties of sweetclover are mentioned with adaptation to forage or green manure use. The booklet has numerous color photos and many data tables and figures.
4022. Mahler, R.L.. 1990. Nitrogen database project - final report.. unpublished report for Dryland Cereal/Legume LISA project.
This project had two components: 1) development of a comprehensive database on winter wheat response to nitrogen fertilizer rates; 2) evaluation of the potential of peas, alfalfa, and wheat straw as nitrogen sources for a following wheat crop in rotation. The database study examined winter wheat yield response to 41 nitrogen rates. When soil test N + mineralizable N + fertilizer N ranged from 101 to 175 kg/ha, a requirement of 2.75 lb N per bushel of wheat was calculated. This agrees with the figure calculated by Leggett in the 1950's, indicating that modern varieties have not changed in their basic nitrogen requirement, when nitrogen fertilizer efficiency is assumed to be 50%. At total available N rates greater than 175 kg/ha, the N requirement per bushel of wheat increased dramatically. Low rates did not show a large increase in efficiency on a per bushel basis. At Moscow, N fertilizer application rates less than 95 kg/ha resulted in greater than 50% N use efficiency. Efficiency declined rapidly at rates above this. The green manure study compared alfalfa, pea, and green wheat straw residues applied at 1, 2, and 3 mt/ha. In general, higher rates of pea and alfalfa resulted in higher wheat yields. The highest yields were with the high rate of pea residue. It was more effective than alfalfa residue, probably due to faster decomposition. Alfalfa provided more N per ton of residue (31 kg/mt) than the peas (29 kg/mt), while straw added 19 kg/mt.
5065. Patten, A.G.. 1982. Comparison of nitrogen and phosphorous flows on an organic and conventional farm.. M.S. Thesis, Dept. of Agronomy and Soils, WSU, Pullman, WA.
Two adjacent farms, one organically managed and the other conventionally managed, located in the Palouse region of eastern WA, were studied for 2 years. Soil organic matter, total N, extractable P, and extractable K tended to be higher in the top 30 cm of soil from the organic farm. Mineral nitrogen in the top 30 cm of soil from the conventional farm was higher than or equal to that of the organic farm. Average long-term changes calculated in soil N and P pools resulted in substantial deficits of 44 and 14 kg/ha/yr, respectively, for the organic farm and 23 and 5 kg/ha/yr for the conventional farm. However, nutrients deficits were not reflected in lower soil N and P levels in the plot area tested on the organic farm as compared to the plot area on the conventional farm.
6738. Stickler, F.C. and L.R. Frederick. 1959. Residue paritcle size as a factor in nitrate release from legume tops and roots.. Agonomy J. 51:271-274.
Tested different particle sizes of tops and roots of alfalfa, sweetclover, red clover, and white clover. Coarse particles immobilized less N with alfalfa and white clover, but not red clover. Most treatments immobilized some N for the first 40-50 days, after which net nitrate release curves tended to become parallel. There was greater release of nitrate and recovery from tops than from roots. After 100 days incubation, recovery ranged from 43% for alfalfa, 34% for sweetclover, 25% for red clover, to 19% for white clover.
7972. Sims, J.R., M.K. Muir, and A.E. Carleton. 1968. Evidence of ineffective Rhizobia and its relation to the nitrogen nutrition of sainfoin (Onobrychia viciaefolia).. IN: C.S. Cooper and A.E. Carleton (eds.). Sainfoin Symposium. MT Agr. Expt. Sta. Bull. 627.
7850. Koala, S.. 1982. Adaptation of Australian ley farming to Montana dryland cereal production.. M.S. Thesis, Dept. of Plant and Soil Sci., Montana St. Univ., Bozeman, MT 59717.
This study examined the potential to adapt the ley farming system used in Australia to dryland cereal production in Montana. The ley system alternates a grain crop with a self-seeding forage legume. The legumes tested in this study included 5 Australian medics, 7 subclovers, 2 lupins, fababean, and a native Montana black medic. One full cycle of the system was completed. All grain yields (spring wheat) were higher after the legumes than after fallow. Soil water to 120 cm was similar in all plots at wheat planting. The black medic treatment had the highest water use efficiency (100 kg grain/cm) and fallow the lowest (55 kg grain/cm). There were higher levels of soil nitrate after the legumes than after fallow. Re-establishment of the legumes after wheat ranged from 3 to 93% ground cover, with black medic being the highest. Overall, black medic from Montana performed best in this study.
7885. McGuire, C., R. Lockerman, R. Speilman, L. Welty, L. Prestbye, R. Engel, J. Sims, and J. Bunker. 1989. Nitrogen contribution of annual legumes to the grain protein content of Clark barley production.. Applied Agric. Res. 4:118-121.
8064. Welty, L.E., L.S. Prestbye, R.E. Engel, R.H. Lockerman, R.S. Speilman, J.R. Sims, R.A. Larson. 1988. Nitrogen contribution of annual legumes to subsequent barley production.. Applied Agric. Res. 3:98-104.
10079. Cowie, A.L., R.S. Jessop, D.A. MacLeod and G.J. Davis. 1990. Effect of soil nitrate on the growth and nodulation of lupins (Lupinus angustifolius and L. albus).. Austral. J. Expt. Agric. 30:655-659..
The effect of increasing external nitrate concentration on the nodulation of Lupinus albus and L. angustifolius lines was examined in two sand culture experiments. In the first experiment four lines, three L. albus and one L. angustifolius, were grown at nitrate concentrations of 0, 2, 8, 16, and 30 mmol/L for 49 days. Increasing the nitrate concentration reduced nodule weight in all varieties to a similar extent. In a second experiment, 18 L. angustifolius lines were grown at nitrate concentrations of 2 and 8 mmol/L for 49 days. The ratio of nodule weights at the 8 and 2 mmol/L nitrate treatments varied widely, from 23 to 71%, between the lines. There appears to be potential for selection of L. angustifolius varieties able to maintain nitrogen fixation at increased levels of soil N.