Browse on keywords: erosion WA variable fertilizer application
Search results on 12/09/18
3210. Bhatti, A.U.. 1990. Spatial variability and geostatistical estimation of soil properties and wheat yield on eroded lands in the Palouse region.. Chpt. 3, PhD. Dissertation, Dept. of Agronomy & Soils, Washington State Univ., Pullman, WA 99164.
Spatial variability of organic matter, soil P, and wheat yields was studied using classical statistical and geostatistical approaches on two commercial wheat farms in the Palouse region of eastern Washington. Geostatistics indicated strong spatial relationship of soil properties and wheat yields with a range of influence of 50-200 m. The two sites differed greatly in spatial patterns due primarily to differences in topography and the extent of erosion and topsoil loss. As a consequence of topsoil loss and reductions in organic matter, it was demonstrated that spatial patterns in yield and soil phosphorus were strongly correlated with organic matter patterns. Remote sensing of soil organic matter and the use of geostatistics offers a way to quickly assess spatial patterns in grain yield and available phosphorus.
3220. Bhatti, A.U.. 1990. A comparison of criteria for dividing eroded wheat fields into different management zones.. Chpt. 2 PhD. Dissertation, Dept. of Agronomy & Soils, Washington State univ., Pullman, WA 99164.
The study examined possible criteria for dividing dryland grain fields into management units for variable fertilizer (and other input) management. Criteria evaluated included fertility status, organic matter content, available water content, soil pH, erosion class, and wheat yield. Erosion class and soil pH were not satisfactory, but the other criteria were acceptable since they all allowed division of the field into three zones with significantly different grain yields as well as different nitrogen fertilizer rates (ranging from 0 to 90 kg N/ha). For each criterion, the field-averaged rates of recommended N were about 35 kg/ha, which is much lower than the grower's typical uniform application of 73 kg N/ha. Generally, the lowest N rates were recommended for eroded hilltops where productivity was low. The two best criteria appeared to be soil organic matter content and grain yield, as they accounted for P deficiency in the eroded zones. Remote sensing can now assess spatial patterns of organic matter on bare soil, thus providing a quick and easy way to delineate production zones.