143

 Reductions in yields due to early-season moisture stress appeared

minimal for crops planted during the local, traditional planting season

at the initiation of the rains in March. The unusually slow start of

the rainy season during the field trial apparently decreased seedling

emergence. The high-density, first-planting treatments had 150% the

number of plants of the low-density treatments, but yielded only 13%

more grain. The densities in the "low emergence" plots were about 75%

of the low- density treatments. Therefore, even a 20% reduction in

yield among the low-emergence plots compared to the regular low-density

plots would still have doubled yields for the plots of the second-

planting season. Delays in second growth season subjected the crop to

more late-season rain, greater losses of nutrients due to increased

leaching, and associated reductions in grain yields.


 Nutrient Leaching



 Soil solution and Mehlich I-extractable concentrations of Ca, K,

 and Mg were differentially affected by fertilizer and simulated rainy-

 season water treatments to the soil columns. The soil-solution

 concentrations of Ca, K, and Mg declined earlier in the season under a

 high-rainfall simulation than for a similarly fertilized low-rainfall

 regime. Higher rainfall caused more washing of the larger pores

 (preferential flow). Compared to columns receiving similar quantities

 of an all-preplant fertilizer treatment, split-fertilizer applications

 composed primarily of K, NO3, and NH4 resulted in lower overall

 concentrations of soil-solution Ca, K, and Mg early in the season. The