Soil Nitrogen Enrichment Research Articles

Reconstruction of the historical changes in mycorrhizal fungal communities under anthropogenic nitrogen deposition.

Archived soil samples (1937-1999) and historic air quality data from the Los Angeles Basin were used for reconstructing the record of change between atmospheric NO(x) loads, soil delta(15)N values and the diversity of arbuscular mycorrhizae (AM), which are ubiquitous plant-fungus mutualists that control plant community productivity. A tripling of atmospheric NO(x) loads between 1937 and the 1970s was paralleled by soil nitrogen enrichment (delta(15)N = 3.18). From 1975 onwards, atmospheric NO(x) declined, but soils became nitrogen saturated (delta(15) N = -4 and NO(3)-nitrogen = 171mgkg(-1)). The shifts in the AM community followed 28 years of atmospheric nitrogen enrichment and coincided with the onset of soil nitrogen saturation. Such changes were manifest in the loss of AM productivity, species richness (one species per year), three genera (Acaulospora, Scutellospora and Gigaspora) in the spore community and Gigaspora within the roots. Nitrogen enrichment also enhanced the proliferation of potentially less mutualistic species of Glomus. Autoregressive models implied that such patterns will persist and be driven by soil nitrogen cycling patterns. Chronic nitrogen enrichment from air pollution thus alters the diversity and mutualistic functioning of AM communities, which, in turn, may influence the plant community.

Spatial variability of nitrate nitrogen in soil during the growing season of maize, cowpea and soybean

The nitrogen advantage of legumes in crop rotation systems is well known, but the nitrogen advantage from legumes to associated crops in an intercropping system is unclear. The objective of this study was to determine whether plant-available nitrogen is released by cowpea and soybean during the growing season, since this could mean a saving in nitrogen fertilizer for an associated crop in an intercropping system. Nitrate nitrogen levels were monitored monthly throughout two growing seasons on cowpea, soybean and maize plots at two localities. There was no evidence of nitrogen enrichment of soil by the legumes in the early growing stages, but nitrogen was released into the soil when the legumes reached maturity, about four months after planting. The nitrogen enrichment of the soil occurred only within the legume rows, since no differences in nitrogen levels were found between the rows. This suggests that the mechanism of nitrogen enrichment of soil from these legumes is the rapid mineralization of nitrogen from roots and/or nodules when they reach maturity. It is, therefore, unlikely that legumes can provide a nitrogen advantage to associated crops within an intercropping system in the same season.

Past, present and future utilisation ofMyrica gale (Myricaceae)

The development ofM. gale oil as an insect repellent has created a requirement for cultivation of the plant. Botanical evidence indicates thatM. gale is likely to thrive on well—aerated acid peatland and could become a valuable crop on land of low agricultural value. Plant growth would be enhanced by the prevention of grazing and could be combined with softwood forestry since the trees would benefit from soil nitrogen enrichment thanks to the symbiotic association ofM. gale andFrankia. The economics of oil production would be improved if additional compounds of value such as pharmacologically active fiavonoids could be extracted from the by-products.

Farmer as Scientist: Bringing Farmers Knowledge to Research

Pacific ViewpointVolume 33, Issue 2 p. 145-150 ArticleFree Access Farmer as Scientist: Bringing Farmers Knowledge to Research Anan Polthanee, Anan PolthaneeSearch for more papers by this author Anan Polthanee, Anan PolthaneeSearch for more papers by this author First published: 01 May 1992 https://doi.org/10.1111/apv.332005Citations: 1AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References 1 Berlyn, G. P. 1972. Seed germination and morphogenesis. In T. T. Kozlowski (ed.) Seed Biology New York: Academic Press 2 Chambers, R., A. Pacey and L. A. Thrupp 1989 Farmer First: Farmer innovation and agricultural research North Yorkshire: Intermediate Technology Publications 3 T. M. Ching 1972 Metabolism of germinating seeds. In T. T. Kozlowski (ed.) Seed Biology New York: Academic Press, 4 Deanon J. R. 1967. Eggplant, tomato and pepper. In J. E. Knott (ed.) Vegetable Production in Southeast Asia Laguna: University of the Philippines Press 5 Ghildyal, B. P. 1978 Effects of compaction and puddling on soil physical properties and rice growth. In Soil and Rice Laguna: International Rice Research Institute 6 IRRI. 1975. Annual Report 1974 Los Banos: International 7 Rice Research Institute Koller, D. 1972. Environmental control of seed germination. In T. T. Kozlowski (ed.) Seed Biology New York: Academic Press 8 MacGillvray, J. H. 1961. Vegetable Production New York: McGraw-Hill 9 Ruschel, A. P., E. Solani and Vose P. B. 1979. Nitrogen enrichment of soil and plant by Rhizobium Phaseoli-Phaseolus Vulgaris Symbiosis PI. Soil 51: 425- 29 10 Sharma, P. K. and S. K. De Datta. 1985. Effects of puddling on soil physical properties and processes. In Soil Physics and Rice Los Banos: International Rice Research Institute Citing Literature Volume33, Issue2May 1992Pages 145-150 ReferencesRelatedInformation

Studies on Maize‐Legume Intercropping and their Residual Effects on Soil Fertility Status and Succeeding Crop in Upland Situation

AbstractTo examine the advantages of cereal‐legume intercropping system with maize as main crops, field studies conducted for two years on sandy upland loamy soils in Bihar plateau, India, indicated maize‐groundnut as the best system. Yield advantages were noticed between 22–44 % over sole maize cropping. Different production indices largely indicated the same pattern in ranking intercropping treatments. Of the other legumes used, mung also showed potential whereas cowpea and soyabean did not. Increasing cropping intensities through use of interspace by legume did not significantly reduce maize yield, particularly in combination with groundnut and mung. Soil nitrogen enrichment through legume cultivation could be noted through examination of soil test values and yield of succeeding wheat crop. Wheat, however, did not show its promise as a follow‐up crop without input of water and fertilizer.

Nitrogen enrichment of soil and plant byRhizobium phaseoli-Phaseolus vulgaris symbiosis

Incubation of 25 and 30 day old nodulated plants ofPhaseolus vulgaris for periods of 24 h and 72 h under 15-dinitrogen atmosphere indicated nitrogen enrichment of soil compared with soil free of plants and with other plants under the same experimental conditions. This indication of release from the root-nodule system is discussed.