Browse on keywords: erosion WA landscape management
Search results on 12/16/18
3288. Pan, W.L. and A.G. Hopkins. 1991. Plant development, and N and P use of winter barley. I Evidence of water stress-induced P deficiency in an eroded toposequence.. Plant Soil 135:9-19.
Winter barley was grown at three landscape positions of a representative toposequence in the Palouse region to identify soil factors which limit plant development and nutrient use efficiency in the eroded slope positions. Subsurface P was severely deficient at eroded ridgetop and sideslope positions. Drying of surface soil during the growing season prevented roots from using much surface applied P. This moisture stress-induced P deficiency suggests that deep placement of P is needed to build subsoil P levels for enhanced productivity on these eroded sites.
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.
10287. Bhatti, A.U., D.J. Mulla, and B.E. Frazier. 1991. Estimation of soil properties and wheat yields on complex eroded hills using geostatistics and thematic mapper images.. Remote Sensing Environ. 37:181-191.
Spatial variability of organic carbon, soil P, and wheat yields was measured in eastern Washington using classical statistics and geostatistics. Organic carbon content was estimated from Landsat Thematic Mapper images. Goestatistics revealed strong spatial correlations relative to classical statistics. The spatial patterns were associated with changes in surface organic matter content across the landscape resulting from extensive erosion.
10406. Pan, W.L. and A.G. Hopkins. 1991. Plant development, and N and P use of winter barley. II. Responses to tillage and N management across eroded toposequences.. Plant Soil 135:21-29.
Winter barley was grown at three landscape positions of a representative toposequence in the Palouse region. Direct drilling (no-till) into crop residues increased yields by 16% over conventional tillage at an eroded ridgetop position, despite early season growth inhibition. Tillage system had no effect on grain production at other landscape positions that featured higher overall yields. Short-term benefits of no-till systems may be most evident at slope positions where water use is most limited.