ISSN:
1573-5036
Keywords:
Acetylene reduction
;
Conservation tillage
;
Conventional tillage
;
Glycine max L.
;
Merr No-tillage
;
Rhizobium japonicum
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary Tillage has been shown to affect the uptake of phosphorus (P) and yield of soybeans, [Glycine max (L.) Merr.], but there is little information concerning the effects of P fertilization on nitrogen (N2) fixation in soybeans under no-tillage. Two field experiments were conducted in 1980 and 1981 to determine the effects of soil P on N2 fixation under no-tillage and to study the interaction of P fertilization and tillage of N2 fixation, nutrient uptake, and yield of soybeans. In Exp. I, P was applied in 1977 at five rates up to 384 kg P ha−1 and the effects of residual soil P were evaluated in 1980 and 1981 under no-tillage management. Nitrogen fixation rates, as measured by acetylene reduction assay, were significantly affected by soil P in Exp. I, but the assay proved to be a poor technique for estimating total plant N in these tests. Acetylene reduction rates and plant P increased rapidly as soil P increased from 2 to 20 mg kg−1, with little additional increase above 20 mg P kg−1. In Exp. II, rates (0, 32, 64, and 128 kg P ha−1) and time (fall, spring and fall plus spring) of P application were compared under conventional tillage and no tillage. However, plant P increased with increasing levels of applied P. Applied P had no affect on acetylene reduction rates but rates were greater for no-tillage than conventional tillage at the V9 and R5 stages of growth in 1981. Plant uptake of P was more efficient under no-tillage than under conventional tillage in 1980 and 1981. Application of 64 kg P ha−1 under no-tillage resulted in equivalent plant P levels as the 128 kg P ha−1 applied under conventional tillage.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02374993
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