TILLAGE AND FURROW DIKING EFFECTS ON WATER-BALANCE AND YIELDS OF SORGHUM AND COTTON
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Information on the combined effects of deep or no-tillage together with furrow dikes (small earthen dams constructed in the furrow) on water conservation in semiarid regions is limited. The purpose of this study was to compare the amount of rain conserved and the yields of forage sorghum [Sorghum bicolor (L.) Moench] and cotton (Gossypium hirsutum L.) as affected by furrow dikes and tillage for a 3-yr period. An Olton clay loam (fine, mixed, thermic Aridic Palcustoll) was alternately cropped to cotton and sorghum. Forage sorghum was grown in (i) disk or (ii) chisel-disk tilled 16 by 23.8 m field plots with and without furrow diking. Cotton was grown in rotation following sorghum after (i) conventional moldboard-disk or (ii) no-tillage, with furrow dikes in one-half of the tillage treatment plots. Crop yield, rainfall amount, soil water content, and runoff of natural rainfall and of simulated rainfall, applied at 80 mm h-1for 1 h, were measured. Compared with conventionally tilled undiked plots, cumulative nonponded infiltration of simulated rainfall was significantly greater with no-tillage treatments and greater (not significant) in furrow-diked treatments. Runoff of natural rainfall from plots with furrow dikes averaged = 22 mm less than from undiked plots, and it was as much as 57 mm less; however, runoff from diked fields was observed. Under the conditions of this 3-yr study, diking did not significantly increase crop water use and yield, but no-tillage significantly increased crop water use and yield 1 yr. We conclude that furrow dikes installed during the growing season did not increase water conservation and crop yields under the conditions of this 3-yr study due to seasonal dike consolidation that reduced the detention capacity and to the limited runoff from level fields. We also conclude that no-tillage is more effective than chisel tillage for increasing water conservation and crop yields for the conditions of this study.