Nutrient depletion is one of the major causes that contribute to decline in soil productivity in the highlands of Ethiopia. It is generally a reversible constraint as long as soil test based fertilizer application is in place. However, Ethiopian subsistence agriculture has suffered for years due to lack of proper knowledge to combat nutrient depletion. To date, blanket application is the tradit...

Present production of rice is far below its reported potential yield because of being Ndeficiency, the major constraint. Because of poverty, small farmers have to rely on native soil N-supply. Between wheat harvest and rice transplanting, a dry-to-wet season transition (DWT) period exist with changing soil moisture from aerobic to anaerobic and a large amount of native soil N loss is hypothesiz...

Riparian forests can remove large amounts of nitrate from the groundwater discharges of adjacent uphill croplands. We review the mechanisms that could account for NO3 removal. Denitrification is hypothesized to be important, but measurement problems limit the relevant field data. We used large chambers (1-20 mZ) and tunable-diode laser infrared spectrophotometry to measure nitrous oxide (NzO) e...

Incubation experiment was conducted on four soil types in Nigeria using cattle dung (CD) at the rate of 2.5g/kg soil ( 5 t ha), Urea fertilizer at the rate of 0.1g/kg soil ( 200 kg ha ) and cattle dung (2.5g/kg soil) combined with Urea 0.05g/kg soil (100 kg ha) as treatments. The objective of the experiment was to compare the rate of OC, NH4 – N, NO3 – N and available P release on soils selecte...

23 K.G. Cassman, P.W. Singleton b and B.A. Linquist International Rice Research Institute, Manila, Philippines NiFTAL Project, 1000 Holomua Ave, Paia, Hawaii, USA (Accepted 14 December 1992 Although biological N2 fixation (BNF) by legumes can provide significant N inputs to crop systems on highly weathered tropical soils, potential inputs from BNF largely depend on soil P supply. We compared th...

in order to study the competition effects of redroot pigweed (amaranthus retroflexus) and millet (panicum miliaceum) on maize performance under different rates of n fertilizer, a field experiment was conducted in 2009 in the research fields of tarbiat modares university in tehran as a randomized complete block design with factorial arrangement of treatments and three replications. accordingly, ...

in drought stress condition, it is important to estimate the n and k requirement of sugar beet. a drought-tolerant sugar beet genotype, bp karaj, was evaluated in split plot factorial design based on a randomized complete block design with four replications at motahari research station, karaj, iran for three years. main plots were allocated to irrigation treatments including normal irrigation (...

There is currently limited understanding of the contribution of biological N2 fixation (diazotrophy) to the N budget of large river systems. This natural source of N in boreal river systems may partially explain the sustained productivity of river floodplains in Northern Europe where winter fodder was harvested for centuries without fertilizer amendments. In much of the world, anthropogenic pol...

Low soil fertility and high weed infestation are the main culprits for the declining maize production inWestern Kenya. Technology packages to address these constraints exist, but their effectiveness is likely to be influenced by variability in soil types and farm management practices in the region. Trials were conducted during the 2008/2009 cropping seasons to investigate the nutrient use e...