Effect of cropping systems on nitrogen availability in rice monitored through soil solution nitrogen
1998
Padilla, J.L. | Egdane, J.A. | Laureles, E.V. | Ito, O. | Olk, D. (International Rice Research Inst., P.O. Box 933, 1099 Manila (Philippines))
Double or triple cropping of puddled rice has been widely practised by farmers in South and Southeast Asia to achieve higher land productivity since the introduction of high-yielding and nitrogen responsive varieties in the early 1960s. Crop intensification, however, creates imbalance in the supply of nutrients for normal crop growth, thus, causes yield stagnation or, in some cases, yield decline. The soil gets aerated during the growth of the non-rice crop permitting organic matter and the turnover of nutrients especially N. The present study aims to determine the effect of continuous cropping on available nitrogen as affected by cropping sequence and timing of residue incorporation. Nitrogen in the soil solution which is in close contact with the root system may be a good indicator of the balance between soil N supply and plant N uptake. Preliminary results indicate that under both cropping systems (rice-rice and rice-maize), early incorporation of the rice straw caused higher soil solution N compared to the maize stubble early incorporation but the difference is not significant. This could be due to the slow decomposition of the lignin component of the maize residue. Nitrogen concentrations measured at 3, 7, 10 and 14 cm away from the rice hills were similar. It was shown in the study that soil solution N is in a dynamic state and reflects the balance in supply and demand for N between the soil and the plant
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