Intensive management is crucial for optimizing hardwood plantation success, and nitrogen (N) nutrition management is one of the most important practices in intensive management. Because management of short-rotation woody crop plantations is a mixture of row-crop agriculture and plantation forestry, we tested the usefulness of an agronomic budget modified for deciduous perennial trees for estima...

Nitrogen (N) pollution is emerging as one of the most important environmental issues of the 21st Century, contributing to air and water pollution, climate change, and stratospheric ozone depletion. With agriculture being the dominant source, we tested whether it is possible to reduce agricultural N pollution in a way that benefits the environment, reduces farmers' costs, and increases fertilize...

The use of the 15N label for agronomic research involving nitrogen (N) cycling and the fate of fertilizer-N is well established, however, in the case of long term experimentation with perennial crops like citrus, coffee and rubber tree, there are still shortcomings mainly due to large plant size, sampling procedures, detection levels and interferences on the system. This report tries to contrib...

We investigated the variation in leaf nitrogen to phosphorus ratios of tropical tree and liana seedlings as a function of the relative growth rate, whole-plant water-use efficiency, soil water content and fertilizer addition. First, seedlings of 13 tree and liana species were grown individually in 38-l pots prepared with a homogeneous soil mixture. Second, seedlings of three tree species were g...

Fertilizer use is environmentally unsustainable in South Asia. Ideally, farmers would follow optimal fertilization rates for crops based on scientific recommendations. However, there ample evidence why under-fertilize or over-fertilize their crops. Important amongst them that farmers' attitude to risk influences decisions fertilizer use. This paper reviews studies the effects of use, timing app...

Nitrogen utilization by corn (Zea mays L.) is influenced by the form of inorganic N present in the root zone. A field experiment was conducted on Enon sandy loam (fine, mixed, thermic Ultic Hapludalf) to determine N use efficiency and its partitioning in various plant parts of corn. Ammonium nitrate labeled either as NH4-N or NO3-N and applied at 50, 100, or 200 kg N ha" was evaluated. Microplo...

Microbial community structure and functions of rhizosphere soil of rice were investigated after applying low and high doses of nitrogenous fertilizer and Phomopsis liquidambari. Average well color development, substrate richness, catabolic diversity and soil enzymes activities varied after applying N-fertilizer and P. liquidambari and were greater in P. liquidambari treated soil than only N-fer...

The most important problem in achieving high yields in rice is how to increase the nitrogen (N) absorption at each growth stage without reducing the percentage of ripened grains. Proper amount and timing of application could reduce N losses and increase fertilizer use efficiency while cost of production is also reduced and yield is increased. In order to avoid losses and to use soil-and fertili...

Production of Mrenda (Corchorus olitorius) in Kenya has been low due to various reasons, such as poor agronomic practices like incorrect fertilizer rates. Observations from the Mrenda growing areas showed that there is high unmet demand for crop in local market and even for export. This is due to yields being low, 2-4 tons/ha as compared to expected yield of 5-8 tons/ha. Therefore, the main obj...

A field study was conducted on hummocky terrain at the Manitoba Zero Tillage Association Research Farm near Brandon, Manitoba, Canada to determine the variability of crop yield as related to landscape position, soil properties, weed populations and plant disease. This information was used to develop a method for delineation of management units related to precision farming. Variable-rate fertili...