Rice Yield and Soil Chemical Properties as Affected by Precision Land Leveling in Alluvial Soils

Abstract

In 1998 and 1999, two soil series representative of a large percentage of rice (Oryza sativa L.) growing hectarage in the Mississippi Delta were sampled in increments to a depth of 120 cm. Measurements were made to determine how extractable levels of Ca, K, Mg, Na, P, and Zn as well as the total N content and soil pH varied with respect to soil profile depth. Total N, extractable P, Zn, Ca, and pH all tended to decrease with depth while Na tended to increase. Only small differences were seen in Mg and K concentrations. An on‐farm study was conducted in 2000 and 2001 to further investigate the effects of precision land leveling on pH and concentrations of organic matter and extractable nutrients. This study was conducted on seven farms, all of which possessed yield monitor–equipped combines. Field elevation sheets and GPS/GIS technologies were utilized to investigate soil nutrient and yield data for areas of cut and fill at each location. Yields were lower in the cut areas than the fill areas on five of the seven fields. Results from the soil nutrient data were similar to those findings in 1998 and 1999. A nutrient deficiency was apparent in only one of the five fields where yields were reduced. However, the percentage yield loss in the cut areas compared with the fill areas was directly proportional to the volume of soil moved per hectare during the precision land‐leveling process (r2 = 0.78). This research indicates that yields can be reduced after precision land leveling in many soil types, but the reduction may or may not be nutrient related.