Browse on keywords: fertility landscape management
Search results on 06/18/13
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.
5791. Reichenberger, L. and J. Russnogle. 1989. Farming by the foot.. Farm Journal, March 1989, 113(6):11-18.
These articles report on the development of more landscape-intensive crop management in a number of states. Soil variability is a universal fact, and more growers are farming by it rather than field boundaries. Some are using grid systems of 3-10 acres to delineate management units. Computerized fertilizer applicators help make it feasible, as do new technology such as on-the-go nitrate and organic matter read-out, and yield mapping. Montana State Univ. researchers Jeff Jacobsen, Jerry Nielsen, and Pat Carr found yield variations in Montana wheat and barley fields ranging from 25-75 bu/ac in one field, 23-58 in another, and 22-35 in a third one. Each had received a uniform rate of fertilizer. Development of a soil variability map is a first step, and infrared photography can add more detail. Then create a soil management map that includes crop history. Then take soil samples from the management units to develop fertilizer recommendations. The GPS satellite system will enable very precises location in fields for intensive management. Farm machinery moving 7-10 mph would get a reading every 10-20'. Kansas State researchers have developed an on-the-go yield monitor for the combine. University of Nebraska researchers have a machine that recognizes weeds and only sprays herbicide then. Purdue researchers have an organic matter sensor that mounts on a tillage implement.
9633. Hanson, L.D., M. Warner, J.R. Schafer and E. Vasey. 1989. Automating field operations for variable conditions.. Agronomy Abstracts, p. 316. Amer. Soc. Agron., Madison, WI..
Our objective is to tailor fertilizer and other chemical applications to variable field conditions in a practical, cost effective system. Auhtors have been working with soil management PC software for several years. In 1988 a new program was prepared to run in real time on a laptop computer on board a field sprayer to record post emergence spot sprayed areas in sugar beets. Field location control came by interfacing a distance measuring device with the computer. The lateral dimension location was fixed by implement width and pass number. The prototype system was a combination of a wheel revolution counter, a SHARP4502 laptop computer and a program named "weed tracker". The data file created in the mapping phase of the operation can be used later to automatically spray or control other operation in the same field. The developers of the system are working with a Minnesota electronics manufacturer to market a commercial version of the prototype.
9650. Jacobsen, J.S.. 1989. Fertilizing soils, not fields in semiarid regions.. Agronomy Abstracts, p. 316. Amer. Soc. Agron., Madison, WI.
Fertilizer management has traditionally treated farm fields as homogeneous units. Many fields however, contain two or more soils with different crop yield potentials and chemical properties. Identification of soil management units within a field and implementing novel fertilization practices to match soil productivity differences would potentially improve efficiency.
10070. Mahler, R.. undated. Catena management in northern Idaho.. unpublished handout for Extension agent training.
In northern Idaho, water is often not limiting to crop production. Also, nutrient use efficiency is lower than in drier areas. Where annual precipitation is <17", fall application of all N fertilizer is best. But as rainfall increases, nutrient use efficiency can be increased by applying a greater share of N in the spring. Fertility experiments have shown that growers are probably underfertilizing bottomland positions and overfertilizing slopes for maximum net return from fertilizer. Several questions need to be answered to help improve nutrient efficiency. Is the value 2.7 lb N/bu wheat linear? Research results indicate that only 2.4 lb N/bu is needed at 80-90% of maximum yield. Is residual N used as efficienctly by plants from surface layers versus subsurface layers? What is the best approach to estimating N mineralization rates in a soil? Rates in northern Idaho can vary as much as 100% depending on weather conditions.
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.
11224. Carr, P.M., G.R. Carlson, J.J Jacobsen, G.A. Nielsen, and E.O. Skogley. 1991. Farming soils, not fields: A strategy for increasing fertilizer profitability.. J. Prod. Agric. 4(1):57-61.
Grain yield and net returns were measured on individual soil units within a field and were found to vary significantly by soil type. When soil units were fertilized individually, there was improved returns in some fields but not others. Drought conditions may have influenced the results.