Soil and nutrient management

The market for organic vegetables is increasing. As conventional farmers transition fields to organics to meet this demand, there is a need for better organic nutrient management guidance, especially for nitrogen (N). Organic N management is more challenging than conventional N management due to a higher level of uncertainty surrounding the N supplying capacity of an organically managed soil as well as the constraints of organic fertilizers (supply, application timing and placement, and uncertainty of release rate and amount). As a result, conventional nutrient management strategies may not be appropriate for organically managed systems. With organic N management there is often a higher risk of excessive nitrate-N loss and higher risk of not achieving economic yield targets.

Several new powdered limestone products that are more finely ground (smaller particle size distribution) than products historically used have become commercially available. A major factor influencing the effectiveness of a liming material is its particle size distribution, with smaller particles reacting more quickly. Because lime efficiency estimates for various particle size fractions were established in the 1950’s, there is a need to evaluate current guidelines to determine if they adequately predict liming efficiency for these new products. The objective of this study was to assess the reactivity of commercially available powdered lime products (both calcitic and dolomitic) and various particle size fractions over a year with the goal of evaluating current OSU lime guidelines.

This project is evaluating interseeding of crop crops to improve cover crop establishment after late harvested crops such as sweet corn and processing squash. In Project 1 at the OSU Vegetable Research Farm, a cover crop of oat and crimson clover produced the most cover crop biomass when interseeded at V4 compared to V6 and V8 plantings but may have reduced corn yield slightly because of competition for water or nutrients. Applying Laudis herbicide immediately after interseeding of the cover crop had no impact on cover crop establishment, even when seeds were broadcast on the soil surface and incorporated lightly. Clover did not emerge well in interseeded plots, possibly because it was planted too deeply. Clover establishment was best when seed was broadcast on the soil surface and incorporated with shallow tillage. Cover crop biomass in mid-December averaged less in interseeded plots than in fall-planted plots because the oat cover crops began to senesce.

The overall objective of this three-year project was to provide farmers with updated fertilizer recommendations for snap beans. The goal was to maximize nutrient use efficiency without compromising bean yield and quality. This was accomplished by partnering with commercial bean growers to conduct on-farm research as well as conducting trials at OSU’s Vegetable Research Farm.

Urea is a common nitrogen fertilizer for sweet corn production. This two year project evaluated commercially available urea additives for their potential to provide crop production and environmental benefits. Specifically, experiments were designed to evaluate the efficacy of urea fertilizer products containing a urease inhibitor (Agrotain Ultra), or nitrification inhibitors, or a polymer coated urea product (ESN). Products containing nitrification inhibitors (SuperU and Instinct) were evaluated only in 2014, and found to have efficacy similar to ESN in slowing conversion of urea to leachable nitrate-N. The control treatment in all studies was granular urea without additives.

In recent years, several new powdered limestone products that are more finely ground (smaller particle size distribution) than products historically used have become commercially available. A major factor that influences the effectiveness of a liming material is its particle size distribution, with smaller particles reacting more quickly. Because lime efficiency estimates for various particle size fractions were established in the 1950’s, there is a need to evaluate current guidelines to determine if they adequately predict liming efficiency for these new products. The objective of this study was to assess the reactivity of commercially available powdered lime products (both calcitic and dolomitic) and various particle size fractions over a year with the goal of evaluating current OSU lime guidelines.

Enhanced efficiency fertilizer (EEF) technologies have the potential to improve the crop N use efficiency (NUE) as well as minimize negative environmental losses compared to conventional fertilizers. The EEF fertilizer products consist of urea plus additives (to inhibit N loss). The major pathways for N loss in our sweet corn cropping systems are 1) N leached below the root zone as water soluble nitrate-N (NO3-N), and 2) gaseous ammonia loss (NH3-N) to the atmosphere following a surface urea application.Field studies and a laboratory incubation study were conducted in 2014 to evaluate the potential for benefit from EEF products via reduced nitrate-N leaching. Three products were evaluated: ESN (polymer coated urea), SuperU (prilled urea containing both a urease and nitrification inhibitor), and Instinct (urea + nitrification inhibitor).

In 1978 a survey was done in the Willamette Valley to explore the relationship between soil nutrient values and tissue nutrient concentrations.

The overall objective of this multi-year project is to maximize nutrient use efficiency without compromising bean yield and quality. This year’s project objectives were to: 1) evaluate crop response to P fertilizer at current soil P test levels in grower fields; 2) generate phosphorus (P) potassium (K), and nitrogen (N) nutrient budgets (fertilizer inputs vs. harvest removal); and 3) evaluate relationships among bean root rot disease, plant P uptake, biomass allocation (pods vs. leaves).

The following is a method for cheaply and quickly determining a soil’s nitrate status for the purpose of determining the midseason sidedress fertilizer rate for sweet corn. For information on the pre-sidedress nitrate test (PSNT), see OSU’s nutrient management guide EM 9010-E (Sweet Corn- Western Oregon). The ‘Quick Test’ (QT) has been in use for years in the Salinas Valley of California with good results. Compared to a traditional laboratory test, it is cheaper and test results can be obtained within hours of sample collection. Although this method is semi-quantitative, results from the QT are well correlated with laboratory results.