Browse on keywords: fertility IA
Search results on 05/21/13
493. Arthur, Tom. Feb. 1989. Precision application with Spud-Tech.. American Vegetable Grower, p. 14-17..
A Wisconsin company has developed a computer software system and variable fertilizer applicator for use on farm fields. Soil samples are taken for every 2.3 acres to generate a nutrient map, which is loaded into a PROM chip. The chip is inserted into the on-board computer on the Spud-Nik applicator rig, which can vary the rates of six different materials. Both fertilizer and pesticides can be varied according to soil parameters.
1077. Broadbent, F.E. and F.J. Stevenson. 1966. Organic matter interactions.. Agricultural anhydrous ammonia: technology and use. p. 169-197..
1257. Cerrato, M.E. and A.M. Blackmer. 1990. Comparison of models for describing corn yield response to nitrogen fertilizer.. Agron. J. 82:138-143.
The study compares and evaluates several models (linear-plus-plateau, quadratic-plus-plateau, quadratic, exponential, and square root) commonly used for describing corn response to N fertilizer. All models indicated similar maximum yields, but there were marked discrepancies among models when predicting economic optimum rates of fertilization. Statistical analysis indicated that the most commonly used model, the quadratic model, did not give a valid description of the yield responses and tended to indicate optimal rates of fertilization that were too high. The quadratic-plus-plateau model best described the yield responses.
2181. Gill, G.S. and W.M. Blacklow. 1984. Effect of Great Brome (Bromus diandrus Roth.) on the growth of wheat.. Aust. J. Agric. Res., 35:1-8.
Studied competition between wheat and great brome. Competition with great brome reduced the concentration of nitrogen and phosphorous in wheat shoots. The reduction suggested that great brome competed with wheat for absorption of nitrogen and phosphorous. Competition with great brome also resulted in significant reduction in the grain yield. Reduction in mass per grain was probably due to competition with great brome for water during grain-filling.
2284. Greenland, D.J.. 1971. Changes in the N status and physical condition of soils under pastures.. Soils and fertilizers, 34(3): 237-251.
In the U.S. continuous cropping with inorganic N and herbicide use results in high yields. Would such practices work in Australia or would they result in soil degredation? This paper examines the role of pastures in maintaining soil quality. The study concludes that legume pastures are needed to maintain soil fertility in wheat growing areas. This is due to the high silt/fine sand content of the soil and the relationship between organic matter polysaccharides and soil structure necessary for maintaining soil porosity and water infiltration. T: Effects of a nitrification inhibitor (N-serve) on loss of N from soils during incubation. Mean annual soil N incements in soils under pasture. Changes in N content of soil under continuous fallow-wheat pasture and pasture-wheat rotations.
2385. Hammond, M.W. and D.J. Mulla. 1989. Field variation in soil fertility: its assessment and management for potato production.. Presentation at 28th annual WA Potato Conference.
Spatial variability in potato fields for P and K is common and can lead to yield and quality reductions. The potential for variable fertilizer application allows for an efficient solution to the problem, both from an economic and environmental standpoint. The paper presents an example from an irrigated circle in the Columbia Basin. Fertility maps of the field are presented, showing the spatial variability. This information is used to delineate fertility management zones, which receive different rates. Fertilizer efficiency is shown for both the conventional and variable methods. The variable method increased fertilizer costs about $10/ac. on a 200' grid system, where both P and K were mapped. The program will normally increase profits well beyond this expense.
2396. Hammond, M.W. and D.J. Mulla. 1989. Intensive soil sampling and its use in fertilizer programs.. Presentation at 1989 Irrigated Agr. Fertilizer Conference.
Intensive soil sampling on a small grid in farm fields allows one to determine the spatial variability of nutrient levels and to adjust fertilizer applications accordingly. Data from 100, 200, and 400 ft. grids indicates that results from a 200' grid are adequate, but detail is lost at 400'. Soil information can be put on a computer chip for a given field and then used to drive variable fertilizer and pesticide application equipment.
3356. Jain, J.M., G. Narayanasamy, M.C. Sarkar and M.N. Datta. 1980. An evaluation of nitrification retardation property of Citrullus colosynthis.. J. Indian Soc. Soil Sci., 28(4):480-484.
An evaluation of nitrification retardation property of Citrullus colosynthis cake and its influence on yield and N uptake by wheat. Citrullus colosynthis oilcake was tested as nitrification retarder under laboratory and greenhouse conditions. The same showed NH4-N conservation when applied at the rate of 5 and 10% by weight of urea. Higher rate (20%) of the cake resulted in NO2-N accumulation leading to lower N recovery by wheat.
4077. Mason, J.L. and J.E. Miltimore. 1959. Increase in yield and protein content of native bluebunch wheatgrass from nitrogen fertilization.. Canadian J. Plant Sci. 39:501-504.
Native bluebunch wheatgrass in Okanagan Valley (11" precip.) showed marked response to nitrogen fertilization. Dry matter production doubled with 60N added as ammonium nitrate, protein increased from 3.9 to 6.2 %. Fertilizer also increased ground cover by the desirable grasses.
4518. Molla, M.A.Z., A.A. Chowdhury, A. Islam and S. Hoque. 1984. Microbial mineralization of organic phosphate in soil.. Plant and Soil, 78:393-399.
Phosphate-dissolving microorganisms were isolated from non-rhizosphere and rhizosphere of plants. These isolates included bacteria, fungi and actinomycetes. The mixed cultures were most effective in mineralizing organic phosphate and individually Bacillus sp. could be ranked next to mixed cultures.