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1. Soil Test Interpretation: Saturated Paste, EC, SAR and CECSoils of neutral to alkaline pH of the Western United States often contain elevated levels of soluble salts and / or higher concentrations of sodium. Elevated concentrations of soluble salts limit crop growth and sodium may impact water management. Competent agricultural management of these soils is dependent on laboratory analysis of: soil soluble salts and there composition and the irrigation water soluble salt constituents. Soil analysis based on the saturated... R. Miller |
2. Soil Testing to Improve Phosphorus Management on Intensive Vegetable Farms in HawaiiAccording to a recent survey of soil samples sent to the Agricultural Diagnostic Service Center (ADSC) at the University of Hawaii between October 2002 and September 2003, a majority of the samples showed soil test P (STP) levels in the high or excessive categories. Despite high soil test P, many farmers in Hawaii continue to apply P fertilizers. We began a project to evaluate soil P status on a range of vegetable farms throughout the state, to determine crop response to P fertilizers on soils... J. Deenik, S. Fukuda, R. Hamasaki, R. Shimabuku, R. Uchida |
3. Development of Leaf Sampling and Interpretation Methods for Almond and Development of a Nutrient Budget Approach to Fertilizer Management in AlmondA five year research project on the use of N in orchards crops has been conducted to 1) to develop early season sampling protocols, and 2) to determine the response of Almond to various rates and sources of nitrogen (N) and potassium (K) fertilizers, 3) to develop nutrient demand curves and 4) to conduct a long term assessment of nutrient use efficiency with the goal of improving fertilizer management. Leaf and nut samples were taken at 5 stages of development throughout five seasons to determine... P.H. Brown, S. Saa, S. Muhammad, B. Sanden |
4. Reliability of Soil and Plant Analyses for Making Nutrient RecommendationsNutrient management is dependent on the collection of soil and plant samples for analytical testing and assessment. The quality of the analytical test are subject to bias and precision of the measurements made by the testing laboratory. Failure to understand lab analyses uncertainty can lead to over confidence in the management recommendation. Test uncertainty varies by soil and plant test methods utilized and by performance capability of the testing laboratory. Generally soil methods that provide... R. Miller |
5. Nitrogen Budgeting for Tree CropsIn recent years, nitrogen (N) budgets and the 4 R’s approach (right rate, right time, right placement and right source) to N fertilizer management has been gaining more acceptance. In the N budget and 4 R’s approach, fertilizers are applied in proportion to demand and timed with periods of N uptake. As a result, demand is satisfied in a timely fashion avoiding the application in excess of uptake capacity. While N is required for all plant processes, it is the specific growth and development... S. Khalsa, S. Muhammad, P. Brown |
6. Application of Ion Exchange Resin Membranes to Nitrate Testing in the WestResin membranes have been used since the 1960s to measure P supply from the soil. In the 1990’s the Plant Root Simulator (PRS®) probe was invented to further refine a method to measure N mineralization from soil organic matter. The functional measurement of soil N supply during incubation has been applied to both in situ measures and in lab research studies. Extending the PRS® measurements of N ‘intensity’ or flux to a meaningful number that a plant can utilize was accomplished... K. Greer, E. Bremer, T. Sievers |