Proceedings
Year
| Filter results22 paper(s) found. |
|---|
1. A Field Study of Soil Test Variability, Its Effects on Accuracy of Fertilizer Recommendations, and the Subsequent Effect of Variable Rate Fertilizer Application on Soil Test ValuesThree 2.5 acre blocks were selected for intensive soil sampling from within an approximate 90 acre field which had been partitioned into 35, 2.5 acre blocks by a farm supply dealer. The 2.5 acre blocks had previously been sampled on a central composite grid basis and a variable rate fertilizer spreader (VRS) programmed for fertilizing the field. Three other more intensive sampling techniques were used to sample the 3 blocks selected for more detailed studies. Results obtained showed that soil te... |
2. Alfalfa Response to K Rate, Source and Time of ApplicationThe potassium (K) requirement of alfalfa is greater than that for any other nutrient. Potassium influences several systems within-alfalfa plants, including enzyme activity, carbohydrate production and transport, stomata1 activity: photosynthesis through chlorophyll content and CO, exchange rate, and nitrogen fixation (Munson, 1985). Potassium also markedly influences alfalfa agronomically through yield increases and improvements in forage quality, disease resistance, and overwinter survival. A s... |
3. An Evaluation of Methods for Determining Site-Specific Management ZonesNumerous procedures have been examined for identifymg management areas within fields. Traditional soil surveys give a general understanding of the effects soil mapping units have on crop productivity. In the USA. county soil surveys report the average grain yield of major crops by soil series. Slope position and landform are topographic features thal also have been used to explain water and crop productivity relationships (Mulla et al., 1992; Sudduth et al., 1997). Generally, footslope positions... |
4. Dietary P Management to Reduce Soil P Loading from Pig ManureThe potential use of phosphorus (P) based land application limits for animal manure has increased the importance of optimizing animal feed P management. The specific objectives of this study were to determine the impacts of using high available P (HAP) corn and phytase on 1) P uptake and excretion by young pigs, and 2) total P, PA-P, and water-soluble P (WSP) levels in fiesh manure generated by these pigs during a seven day digestibility trial. Our results show that, compared to the control diet... |
5. Effect of Potassium Rates and Placement on Soil Test Variability Across Tillage SystemsExperiments were conducted from 1994 through 1996 at the Dixon Springs Agricultural Center and the Belleville Research Center to evaluate K rates (60, 120, and 180 Ib KzO per acre) and placement methods in a corn and soybean rotation using chisel tillage (CT) and no-till (NT) practices. Four placement methods were used: surface broadcast, dribble, 10-inch wide surface band over each row, and banding 30 Ibs K20 per acre 2 inches to the side and 2 inches below the planted seed (remainder of the K ... |
6. Effect of Tillage, Rotation, and Nitrogen Rate on Rainfed Corn Yield and Nitrogen UptakeDetermining the long term effect of tillage, rotation and nitrogen rate in typical cropping sequences is important in making sound agronomic decisions. In northeast Nebraska rainfall is the major deternlinant of yield. In 1956 a tillage study was initiated to determine the effect of tillage. rotation and nitrogen rate on corn and soybean yields. Spring plow. disk and no-till treatments were applied to continuous corn and co1-n follo\ving soybeans on a Kennebec silt loam. Five nitrogen rates (0. ... |
7. Effect of Time and Rate of N Application on N use Efficiency and Surface Water Contamination with NitratesNitrate levels in excess of the public health standard of 10 mg N/1 in public water supplies along - with concern about hypoxia in the Gulf of Mexico have drawn renewed interest to improving fertilizer N use efficiency. Prior research has indicated that some farmers may be unkaowingly contributing to these problems. The objectives of this research were to: determine the effect of rate and time of N application on nitrate-N concentrations in water from tile lines and to evaluate the effect of pre... |
8. Foliar Fertilization of SoybeansExtensive research addressed foliar fertilization of soybeans at reproductive stages during the 70s and 80s. The soybean plant has been characterized by markedly reduced root activity during late seed development and increased translocation of nutrients and metabolites fiom other tissue into the seed. This depletion of numents from leaves could result in decreased photosynthesis. leaf senescence. and lower grain yields. Researchers theorized that if nutrients were applied directly to the foliage... |
9. Identifying Critical Sources of Phosphorus Export from Agricultural WatershedsPhosphorus (P) is an essential element for plant and animal growth, and its input to agriculture is necessary to maintain profitable crop and animal production. Eutrophication, the natural aging of lakes or streams brought on by nutrient enrichment, can be accelerated by P inputs to fresh waters from human activities (Carpenter et al., 1998; Schindler. 1977). Eutrophication has been identified as the main problem in surface waters withimpaired water quality (USEPA. 1996). It restricts water use ... |
10. Influence of Sulfur Source on CornSulfur is an essential plant nutrient. Medium and fine texture high organic matter soils in South Dakota usually supply adequate levels of sulfur to plants. Very sandy soils are less capable of supplying sulfur to plants but even these soils usually provide adequate sulfur for plant needs. However, in recent years above average precipitation may have caused leaching of sulfur, possibly resulting in sulfur deficiencies. In addition, spring soil temperatures have stayed cool, likely slowing decay ... |