Effect of tillage, mulching and fertilization on the growth and water use of upland rice (Oryza sativa L.)- corn (Zea mays L.) cropping pattern on an inceptisol in Central Java, Indonesia

Plowing at 20 or 30 cm depth before planting reduced bulk density and soil resistance. Bulk density gradually increased during the rice and corn cropping periods. Bulk density and soil resistance at 0-10 and 10-20 cm depths in the shallow and deep plowed plots did not significantly differ at any growth stage of the crop. Bulk density and soil resistance at 20-30 cm depth of the deep plowed plot were significantly lower with the shallow plowed at early growth stage. Mulching did not affect bulk density. Mulching reduced the estimated total soil water evaporation by 41-48 percent and also the soil temperature at 0-10 cm depth by 3 deg C. However, mulching increased root density. The root density of corn was higher in deep plowed than in shallow plowed plot. Mulching or deep plowing with any level of nitrogen fertilization significantly increased rice root density at 90 DAE. At 150 kg N/ha, deep plowing gave significantly higher corn root density in 30-40 cm depth than the shallow plowing at 60 days after emergence (DAE) but mulching gave significantly higher rice root density than the unmulched at 50 DAE. Nitrogen fertilizer application significantly increased root density, plant height, leaf area index, grain yield, and nitrogen content of grain and straw or stover. It also increased water use efficiency. Plowing depths only had significant effect on corn plant height and leaf area index at 30 days after emergence. Mulching significantly increased plant height of rice at 14 and 90 DAE and of corn at 30 DAE. It also significantly increased corn leaf area index at 30 and 60 DAE. The soil moisture availability during corn cropping was lower than the rice. Mulching significantly increased corn yield by 30%. At any level of nitrogen fertilizer application, mulching increased significantly corn grain yield. The water use model reliably predicted the daily soil moisture content of the root zone of rice and corn. The estimated total transpiration accounted for the 82-96 percent of the variation in grain yield of rice and corn. However, estimated total water use accounted for the 64-82 percent of variation in grain yield