02151nam a2200241 a 450000100080000000500110000800800410001910000210006024500730008126000160015430000110017050000720018152015440025365000100179765000120180765000160181965000110183565000100184665000230185665000130187965300090189265300080190118575132011-06-13       1986    bl uuuu  m   00u1 u    #d1 aBARROS, L. C. G.  aWater use efficiency by corn and beans as affected by mulching rate.  a1986.c1986  a137 f.  aDissertation (Doctor of Philosophy) - Utah State University, Logan.  aField experiments were conducted to study the water-use and water-yield production function of corn and beans as influenced by straw mulch rates (), 3.5, 7.0, and 10.5 t/h) and irrigation. The original and a modified version of PLANTGRO model were used to determine the production function. Evapotranspiration (ET) was estimated from measurements of irrigation plus rainfall and soil water depletion. Evaporation (E) was estimated using a micro-lysimeter and Transformation (T) was estimated as ET minus E. Energy balance components were also measured. Despite a similar ET for mulched and bare soil for both crops, dry matter yields for corn and beans and grain yield for beans were higher for mulch than for bare treatments. Corn grain however decreased with increase in mulch rate. Higher transpiration probably contributed to higher yield under mulched condition, as compared to bare soil. Lower corn grain yield was associated with lower soil tempearature in mulch treated soil. Increased yields in a wet season (1984) for low irrigation for corn and niddle irrigation for beans resulted from mulch treatments as compared to bore soil. In a dry season (1985) beans yield was increased by mulch only at high water levels. The lowest mulch rate was as effective in improving yields, for booth crops, as the highest one. Beans yields were more responsive to mulching than corn. The PLANTGRO model gave good predictions of relative grain and dry matter yield for corn. For beans however it did not simulate the grain yield very well.(...)  aÁgua  aFeijão  aIrrigação  aManejo  aMilho  aPhaseolus Vulgaris  aZea Mays  aBean  aUso