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Download or read book Estimating the Nitrogen Contribution of Legumes to Succeeding Maize on an Oxisol in Brazil written by Walter Truman Bowen and published by . This book was released on 1987 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Legumes managed as green manures may supply all or most of the nitrogen needed by succeeding nonlegume crops for maximum production. To find legumes and management systems most efficient at supplying this nitrogen requires extensive testing of many potential legumes and management systems. As an alternative to extensive crop response studies, a field screening procedure was proposed whereby the supplying capacity of different legumes may be estimated from the amount of inorganic nitrogen released in bare fallow soil following their incorporation. To test the screening procedure, an irrigated dry season experiment was conducted on a Typic Acrustox in Cerrado Region of central Brazil to determine if the quantity of inorganic nitrogen accumulated in fallow soil was proportional to nitrogen uptake by maize (Zea mays L.). After the incorporation of varying amounts of plant material derived from two legumes, mucuna [Mucuna aterrima (Piper & Tracy) Merr.] and soybean [Glycine max (L.) Merr.], inorganic nitrogen that accumulated in fallow soil was measured periodically until maize harvest. Results showed the quantity of inorganic nitrogen accumulated in fallow soil was significantly proportional to nitrogen uptake by maize (r=0.93, p=0.01). the accumulation of inorganic nitrogen in fallow soil and nitrogen uptake by maize were also measured in two separate experiments conducted during the subsequent wet season. Data from these two experiments were combined with the dry season data to reveal a significantly proportional relationship between the quantity of inoganic nitrogen accumulated in fallow soil and nitrogen uptake by maize across all three experiments (r=0.92, p=0.01). Linear regression of the data showed that maize took up 44% (+-6.0%) of the inoganic nitrogen released in fallow soil by 72 to 83 days after planting. Comparisons could not be determined for later dates because mineralized nitrogen was evetually leached during the wet season below the sampling and rooting depth. It was also demonstrated across the three experiments that 81% (+-5.4%) of the inorganic nitrogen released in fallow soil was recovered in aboveground maize plus residual soil inorganic nitrogem (r=0,98,p=0.01). Therefore, the nitrogen suppling potential of legumes may be appropriately estimated by the quantity of inorganic nitrogen relased in bare fallow soil after bincorporation.