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The Influence of Fertilizers and Season on Nonsymbiotic Nitrogen Fixation in Brookston and Bedford Silt Loams 1
Author(s) -
Roberts James L.,
Olson Frank R.
Publication year - 1942
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1942.00021962003400070004x
Subject(s) - loam , citation , agricultural experiment station , mathematics , library science , geography , agriculture , biology , archaeology , computer science , ecology , soil water
O most Indiana soil types, greater crop yields are obtained following fertilization with phosphorus and potassium. Greater yields of nonleguminous crops are expected to hasten depletion of’soil nitrogen. However, in five of seven fields, of the Purdue Experiment Station, the total nitrogen content of fertilized plots is significantly higher than that of unfertilized plots. Since the amounts and kinds of fertilizers used on the experimental plots in general are representative of practices used by Indiana farmers, these facts suggest that the use of non-nitrogenous fertilizers by farmers, even in relatively small amounts, may stimulate nitrogen fixation, either symbiotic, nonsymbiotic, or both. It is well known that the addition of phosphates to soil samples may increase growth and nitrogen fixation by Azotobacter spp., this ̄ being the basis of the Winogradsky test for phosphorus deficiency. Turk (7) 3 reported that KC1 added in the laboratory slightly increased the rate of nonsymbiotic nitrogen fixation in some Michigan soils. The nitrogen-fixing power of soils variously fertilized in the field with amounts of fertilizers commonly used in farm practice has been determined on other occasions (~). If the soil is sufficiently deficient in phosphorus, the addition of even small amounts of phosphates to field soils is expected to increase the nonsymbiotic nitrogen-fixing power of the soil. There does not seem to be a case reported where a potassic salt added to field soils in relatively small amounts definitely influenced the nonsymbiotic nitrogen-fixing power of the soil.