Nitrogen contribution by a legume tree (Paraserienthes falcataria) biomass to a corn crop
2002
Zaharah A.R., Putra Malaysia Univ. (UPM), 43400 UPM Serdang, Selangor (Malaysia). Faculty of Agriculture. Dept. of Land Management | Chintu R., Forest Research Institute Malaysia (FRIM), 52109 Kepong, Kuala Lumpur (Malaysia). | Anuar A.R. | Halimi M.S. | Kadir W,R. (eds.), Putra Malaysia Univ. (UPM), 43400 UPM Serdang, Selangor (Malaysia). Faculty of Agriculture. Dept. of Land Management
In agroforestry land-use system, organic inputs in terms of above-ground (fresh leaves and dry litter) and below-ground (dead and live root biomass) from nitrogen rich tree legumes play a significant role in supplying N to the associated crops. Literature on most agroforestry cropping systems has dealt much on N contribution of tree above-ground biomass to crops (Buresh et al., 1997) zaharah et al., 1999, Kwesiga et al., 1999) Poor documentation on the role of roots (below-ground biomass) is available due the difficulty in undertaking quantitative root studies in the field (Schroth, 1999). This study was carried out to quantify the N contribution to grain corn crop by P. falcataria fresh leaves and roots using superscript 15 N-isotope to label the whole tree and the corn plants, while the roots remained in the soil. Results from this study showed that P. falcataria below-ground biomass has a higher N contribution (57 %) to corn than the above-ground biomass (14 %). The lower recovery from above ground biomass that was surface applied was attributed to the quick N release pattern from the high quality leaves that has little synchrony with the nutrient demand by corn plants. Hence resulting in large N losses and low utilization by crops. The underground biomass had a more conductive decomposition environment for N mineralization and thus a higher N use efficiency. This in situ labeling of tree biomass has proved to be a valuable tool in studying N cycling of above- and below-ground tree biomass and their respective N contribution to the associated crop.
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