Improving soil organic nitrogen and sulfur pools by cover cropping and crop fertilization in soybean-based cropping systems

2021 ◽  
Vol 213 ◽  
pp. 105138
Author(s):  
Cecilia Crespo ◽  
Nicolás Wyngaard ◽  
Hernán Sainz Rozas ◽  
Pedro Barbagelata ◽  
Mirian Barraco ◽  
...  
2022 ◽  
Vol 169 ◽  
pp. 104212
Author(s):  
Jihui Tian ◽  
Kai Wei ◽  
Tao Sun ◽  
Nan Jiang ◽  
Zhenhua Chen ◽  
...  

2017 ◽  
Vol 169 ◽  
pp. 71-80 ◽  
Author(s):  
Juan M. Martínez ◽  
Juan A. Galantini ◽  
Matias E. Duval ◽  
Fernando M. López

1965 ◽  
Vol 16 (3) ◽  
pp. 257 ◽  
Author(s):  
JR Freney

Simazine applications of 1.5 p.p.m. to soil in pots in a glasshouse increased dry matter yields and uptake of nitrogen in corn only when additional nitrogen was applied to the soil. The proportions of protein and non-protein nitrogen in the topgrowth were not affected. Application of simazine at this rate without addition of nitrogen resulted in increased leaf area but did not significantly affect yield. Simazine provided a stimulus to the plant early in its life and enabled it to grow faster than the control plant. When the supply of available nitrogen was exhausted the simazine effect decreased. When incubated with soil, simazine did not increase mineralization of soil organic nitrogen, nor did it have any effect on immobilization of mineral nitrogen. Simazine applied at 0.06 p.p.m. in solution culture increased the yield of corn tops by 36%, the uptake of nitrogen by 37%, phosphorus by 25%, magnesium by 24%, and potassium by 41 %. It had no effect on the yields of roots. The results suggest that simazine increased plant growth by a direct effect on plant metabolism and not through any interaction with the soil.


2020 ◽  
Vol 456 (1-2) ◽  
pp. 355-367
Author(s):  
Lucy M. Greenfield ◽  
Paul W. Hill ◽  
Eric Paterson ◽  
Elizabeth M. Baggs ◽  
Davey L. Jones

Abstract Aims The capacity of plant roots to directly acquire organic nitrogen (N) in the form of oligopeptides and amino acids from soil is well established. However, plants have poor access to protein, the central reservoir of soil organic N. Our question is: do plants actively secrete proteases to enhance the breakdown of soil protein or are they functionally reliant on soil microorganisms to undertake this role? Methods Growing maize and wheat under sterile hydroponic conditions with and without inorganic N, we measured protease activity on the root surface (root-bound proteases) or exogenously in the solution (free proteases). We compared root protease activities to the rhizosphere microbial community to estimate the ecological significance of root-derived proteases. Results We found little evidence for the secretion of free proteases, with almost all protease activity associated with the root surface. Root protease activity was not stimulated under N deficiency. Our findings suggest that cereal roots contribute one-fifth of rhizosphere protease activity. Conclusions Our results indicate that plant N uptake is only functionally significant when soil protein is in direct contact with root surfaces. The lack of protease upregulation under N deficiency suggests that root protease activity is unrelated to enhanced soil N capture.


1967 ◽  
Vol 7 (26) ◽  
pp. 266 ◽  
Author(s):  
R Wetselaar

The mineralization coefficient (M.C.) (the amount of nitrate nitrogen formed in one season in sift, by bare fallowing the soil, as a percentage of the amount of organic nitrogen in the topsoil at the onset of the season) was measured on two soils at Katherine, N.T. The determination of M.C. is regarded as useful in evaluating the 'true' decomposition constant of a soil under annual cropping conditions. Its relation to the 'apparent' decomposition constant is discussed. Tippera clay loam had a mean M.C. of 4.80 per cent, and the fluctuations around the mean were positively related to amount of rainfall. The M.C. for Blain sand dropped from 12.5 per cent in the first year of cultivation to 5.0 per cent in the third and fourth years. The data indicate that the initial high nitrogen yields on the sandy soil will in time decline to a low level unless a legume crop is incorporated in the cropping system.


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