Economic and agronomic effects of four tillage practices on rice produced on saline soils

Conservation tillage practices have come into greater use in recent years. However, studies have shown that using these practices in rice (Oryza sativa L.) on soils prone to salinity problems can reduce yields. An agronomic study was conducted during 1995 and 1996 at the University of Arkansas' Pine Tree Branch Experiment Station near Colt on a soil complex consisting of a Calloway silt loam (fine-silty, mixed, active, thermic Glossaquic Fragiudalf), Calhoun silt loam (fine-silty, mixed, active, thermic Typic Glossaqualf), and Henry silt loam (coarse-silty, mixed, active, thermic Typic Fragiaqualf), in areas that had a history of salinity damage to rice. The experiment was arranged in a randomized complete block design with three replications and four tillage treatments (conventional tillage, deep tillage with a paratill implement, attempted deep tillage with a chisel plow, and no-till) per replication. Enterprise budgets were used to determine the relative profitability of the four tillage systems (conventional, no-till, chisel plow, and para-till), in order to determine whether or not the increased production costs incurred using tillage would be offset by increased returns. Sensitivity, breakeven, and statistical analyses were performed to determine whether there was any significant difference in yields and net returns among tillage practices. No significant difference was demonstrated among the three treatments using tillage; no-till, however, was significantly different from the other three, having considerably lower yields. When averaged across years and treatments, yields from tilled plots averaged 72.15 cwt/acre. Yields from no-till plots averaged 62.37 cwt/acre. Net returns above total costs for tilled plots, when averaged across years and treatments, averaged $230.25/acre. Net returns above total costs for no-till averaged $173.03/acre. It is therefore recommended that some form of tillage be used in order to reduce the concentration of salts in the rice root zone. However, it is not possible to recommend one form of tillage as being superior to the others examined in this study.