Effects of nitrogen fertilizer rates and soybean residue management on nitrate nitrogen in sorghum-soybean intercropping system
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Date
2014-10-11
Journal Title
Journal ISSN
Volume Title
Publisher
SCIENCEDOMAIN international
Abstract
An experiment was carried out in Busia County, Kenya at Emalomba (N 00°25′28.8″ E 034°15′
51.9″), Nambale District to assess the effects of nitrogen fertilizer rates and legume management
options on nitrate nitrogen (NO3-N) under intercropping system. Six soybean residue management
options were considered: Sole sorghum, sorghum + soybean left to maturity, sorghum + soybean
mulched, sorghum + soybean incorporated, sorghum + soybean exsitu and sorghum + soybean
exsitu and plot tilled. Three levels of nitrogen (0kg N ha-1, 40kg N ha-1, and 80kg N ha-1 as urea
were applied as top-dress and treatments arranged in randomized complete block design. Soil
NO3-N was significantly high (P<0.0010) in topsoil with a notable leaching to subsoil due to
precipitation. Control treatments had low soil NO3-N in comparison to other treatments implying
that, use of inorganic fertilizers to supplement soil N is important. Fertilizer application at 40kg N ha- 1 with respect to on-farm soybean residue management was in relation to NO3-N supply was in the
order: sorghum + soybean left to maturity > sorghum + soybean mulched = sorghum + soybean
incorporated. Experimental plots with legume residues removed had significantly (P<0.001) low
NO3-N. High leaf NO3-N observed points to transfer of N to sorghum by nitrogen fixation signifying
importance of intercropping. There was no significant difference between nitrogen fertilizers applied
at 40kg N ha-1 and 80kg N ha-1 irrespective of field managed legume residues. Sorghum
intercropped with soybean left to maturity with nitrogen fertilizer applied at 40 kg N ha-1 reflected
high (P< 0.001) soil NO3-N in comparison to the other management options. It is therefore
recommended as a possible optimum rate and legume residue management option to improve soil
NO3-N among small scale households with stretched socio-economic ability in Busia County.
Description
This article is available at www.sciencedomain.org
Keywords
Nitrogen fertilizer, Intercropping, Nitrate, Sorghum, Soybean, Residue management
Citation
Kebeney, S. J., Semoka, J. M. R., Msanya, B. M., Ng’etich, W. K. & Chemei, D. K. (2014). Effects of nitrogen fertilizer rates and soybean residue management on nitrate nitrogen in sorghum-soybean intercropping system. International Journal of Plant & Soil Science 4(3): 212-229.