Contour grass strips and tillage affect corn production of Philippine steepland oxisols
2000
Thapa, B.B. | Garrity, D.P. | Cassel, D.K. | Mercado, A.R.
Cultivated steeplands in the humid tropics require better soil management systems to meet increasing food demands. The objective of this 4-yr study was to evaluate the following four contour soil management systems for corn (Zea mays L.) production: (i) contour moldboard plowing (CP); (ii) ridge tillage (RT); (iii) natural grass barrier strips plus moldboard plowing (GCP); and (iv) grass strips plus ridge tillage (GRT). Eight successive corn crops were grown in limed and fertilized soil from 1992 through 1995. On a total land area basis (cropped area plus the area occupied by the grass strips), the 1995 mean grain yields for RT (10.8 Mg ha(-1)) and GRT (10.3 Mg ha(-1)) were significantly greater than yields for CP (10.0 Mg ha(-1)) and GCP (9.6 Mg ha(-1)). The corn grain yields for the CP and RT systems before 1995 ranged from 1.3 Mg ha(-1) in 1992 to 8.4 Mg ha(-1) in 1993, while comparable GCP and GRT yields ranged from 1.4 to 7.6 Mg ha(-1). Excluding the area occupied by the grass strips, the GRT system had the highest 4-yr average corn yield (7.3 Mg ha(-1)) followed by the GCP (7.2 Mg ha(-1)), RT (6.9 Mg ha(-1)) and CP (6.7 Mg ha(-1)) systems. Yields improved during the 1994 and 1995 growing seasons when the grass was not permitted to grow as tall. The combination of contour ridge tillage and contour grass strips has potential for sustaining crop productivity on highly erodible steepland soils in the humid tropics.
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