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SUMMARY. Use efficiency of applied nitrogen (N) is estimated typically to be <50% in most crops. In sandy soils and warmer climates particularly, leaching and volatilization may be primary pathways for environmental loss of applied N. To determine the effect ofNfertilization rate on theNuse efficiency (NUE) and apparent recovery of N fertilizer (APR), a replicated field study with 'BHN 602' tomato (Solanum lycopersicum) grown in sandy soils under a fertigated plastic-mulched bed system was conducted using ammonium nitrate as the N source at four different rates (0, 150, 200, and 250 lb/acre). Spring tomato was followed by fall tomato in the same field, a typical cropping sequence in north Florida. Fertigation of N fertilizer was applied weekly in 13 equal doses for both seasons. The highest NUE was 12.05% (spring) and 32.38% (fall), and the highest APR was 6.11% (spring) for the lowest rate of N applied (150 lb/acre). In the fall, APR was unaffected by fertilizer N rates and ranged from 12.88% to 19.39%. Nitrogen accumulation in tomato plants were similar among the three N fertilizer rates applied (150, 200, and 250 lb/acre), though compared with no N fertilizer application, significant increases occurred. Whole plant N accumulation, NUE, and APR declined or remained similar when N rates increased above 150 lb/acre. Additionally, a regression analysis and derivative of the quadratic fresh yield data showed that yields were maximized at 162 and 233 lb/acre N in the spring and fall seasons, respectively. [ABSTRACT FROM AUTHOR]

This paper analyses how specific institutional barriers and drivers affect the success of agri-environmental governance and policy innovations in four case study catchments in Germany, Latvia, Poland and Sweden. Possible adaptations of institutional settings are explored, aiming at increased effectiveness of policies and governance in delivering multiple ecosystem benefits along with reduced nutrient emissions and flood management. Factors of success synthesized from existing examples of innovative policy instruments in the EU and further afield are used to identify barriers and opportunities for the implementation of policy innovations in different institutional settings across the Baltic Sea Region (BSR). Key factors of success include close and trusting cooperation in scheme development, utilization of intermediaries in trust building, an active role of civil society and private sector, spatial targeting and coordination of measures, and result-based and long-term approaches. It is concluded that the effectiveness of measures can be increased by (i) adopting a less prescriptive approach to implementation, (ii) strengthening bottom-up participatory stakeholder learning processes, (iii) fostering cross-sectoral planning and funding initiatives, (iv) creating incentives for local collaborative actions, (v) developing cooperative nutrient management initiatives in the BSR and (vi) developing a systematic and coordinated approach to pilot-testing of new concepts and measures. [ABSTRACT FROM AUTHOR]

Vegetable and fruit consumption patterns in the United States indicate that most people need to eat far more fruits and vegetables to meet the current nutritional guidelines for a healthy diet. Following these guidelines would require more than doubling die harvested acreage for fruits and vegetables and could have serious environmental implications if unsustainable production practices were used. This situation will likely intensify with population growth and climate change. To answer the title question (can we grow organic or conventional vegetables sustainably with out cover crops?), this paper focuses on the high-input, tillageintensive vegetable production practices in the Salinas Valley of California, a region often called "the Salad Bowl of America." This region has a serious problem of nitrate contamination of the groundwater that occurred as the agricultural systems here shifted from agronomic to high-value horticultural crops [primarily vegetables and strawberries (Fragaria ×ananassa)] over the past several decades. This raises questions about the sustainability of past and current vegetable production practices and indicates the need for a radical paradigm shift in nutrient management. Cover cropping is well recognized as a "best management practice" in vegetable production systems, but is still relatively uncommon in many of the most important vegetable production regions hi the United States, including the Salmas Valley. It is argued that cover crops are an essential part of sustainable vegetable production because they provide a comple× suite of unique ecosystem services during fallow periods that complement best management practices during cash crop periods. The reasons that cover crops are uncommon here are discussed and three alternative cover cropping strategies are described to potentially increase adoption of cover cropping in vegetable rotations. These strategies are focused on reducing residue management challenges and include a novel strategy to e×tract the juice from nitrogen-rich, immature cover crops for use as a liquid organic fertilizer in subsequent cash crops. [ABSTRACT FROM AUTHOR]

Onion (Allium cepa) and tropical pumpkin (Cucurbita moschata) combined contribute 13% of the total gross agricultural income (GAI) for vegetable crops in Puerto Rico, which is estimated at $54.5 million. Both crops are usually rotated on an annual basis. In this study, an onion-tropical pumpkin rotation was used to test the effect of fertilizer-nitrogen (N) on agronomic indicators of onion (plant height, number of leaves per plant, leaf color index, and leaf nutrient concentration), yield of both onion and tropical pumpkin, and inorganic N changes in the soil profile. Three fertilizer-N levels (140, 196, 252 kg·ha-1) were applied to onion, followed by 112 and 280 kg·ha-1 of N applied to tropical pumpkin. For tropical pumpkin, N was applied in plots with the lowest and highest fertilizer-N levels from the previous onion crop. Changes in onion agronomic indicators with increasing N fertilization were either not significant or showed no clear trend. There was no increase in total and marketable yields and number of onions with increasing fertilizer-N levels. Tropical pumpkin yields significantly increased with 280 kg·ha-1 compared with 112 kg·ha-1 of N. Using 112 kg·ha-1 as a baseline fertilizer-N application, the value/cost ratio for tropical pumpkin was $12.70 per dollar of fertilizer-N. In low fertilizer-N plots, immediately available inorganic soil N (0 to 30 cm) did not change between the onion and tropical pumpkin crop, but then decreased at the end of the rotation. In high fertilizer-N plots, immediately available soil N greatly increased after onion, but then decreased at the end of the rotation. Potentially leachable soil N (30 to 100 cm) also increased after the onion crop and then decreased after pumpkin. However, in high fertilizer-N plots, potentially leachable soil N remained 44% higher at the end, compared with the beginning, of the rotation. The increased income attainable with the highest fertilizer-N in tropical pumpkin may be offset by greater residual soil N in the lower part of the soil profile, and the potential for this N to have a negative environmental impact. [ABSTRACT FROM AUTHOR]

Summer cover crop rotations, compost, and vermicompost additions can be important strategies for transition to organic production diat can provide various benefits to crop yields, nitrogen (N) availability, and overall soil health, yet are underused in strawberry (F r agaria xananassa) production in North Carolina. This study was aimed at evaluating six summer cover crop treatments including pearl millet (Pennisetum glaucum), soybean (Glycine max), cowpea (Vigna. unjjuiculata), pearl millet/soybean combination, pearl millet/cowpea combination, and a no cover crop control, with and without vermicompost additions for their effects on strawberry growth, yields, nutrient uptake, weeds, and soil inorganic nitratenitrogen and ammonium-nitrogen in a 2-year field experiment. Compost was additionally applied before seeding cover crops and preplant N fertilizer was reduced by 67% to account for organic N additions. Although all cover crops (with compost) increased soil N levels during strawberry growth compared with die no cover crop treatment, cover crops did not impact strawberry yields in the first year of die study. In the 2nd year, pearl millet cover crop treatments reduced total and marketable strawberry yields, and soybean treatments reduced marketable strawberry yields when compared with the no cover crop treatment, whereas vermicompost additions increased strawberry biomass and yields. Results from this study suggest that vermicompost additions can be important sustainable soil management strategies for transitional and certified organic strawberry production. Summer cover crops integrated with composts can provide considerable soil N, reducing fertilizer needs, but have variable responses on strawberry depending on the specific cover crop species or combination. Moreover, these practices are suitable for both organic and conventional strawberry growers and will benefit from longer-term studies that assess these practices individually and in combination and other benefits in addition to yields. [ABSTRACT FROM AUTHOR]

A two-season study was conducted to assess the effects of preplant potassium (K) fertilization rates and sources on the growth and yield of beefsteak tomato (Solanum lycopersicum). Fourteen treatments resulted from the combination of two K sources: sulfate of potash [SOP (0N-0P-42K)] and muriate of potash [MOP (potassium chloride, 0N-0P-50K)] and seven preplant K rates (0, 50, 100, 200, 300, 400, and 500 lb/acre). Soil electrical conductivity (EC) at 4 weeks after transplanting was influenced by the interaction between preplant K rates and sources. When SOP was applied, soil EC increased from 0.4 dS·m-1 with no preplant K application to ≈1.3 dS·m-1 with a rate of 500 lb/acre of preplant IC However, the soil EC steadily increased from 0.4 to 3.0 dS·m-1 as preplant K rates increased from 0 to 500 lb/acre when MOP was used as the nutrient source. The combined effect of the preplant application of K rates and sources influenced the seasonal extra-large and total marketable fruit weight, which increased steadily with K rates, regardless of the sources, from 0 to 300 lb/acre. At K rates between 300 and 500 lb/acre, there were no extra-large and total fruit weight differences among rates when SOP was applied. In contrast, extra-large and total marketable fruit weight declined when rates increased from 300 to 500 lb/acre of K and MOP was applied to the soil. Data demonstrated that plots treated with MOP at rates higher than 300 lb/acre of K increased soil EC and caused a decline on extra-large and total marketable fruit weight of tomato. [ABSTRACT FROM AUTHOR]

This review integrates information from common organic amendments used in conventional vegetable production, including 1) cover crops (legumes and nonlegumes), 2) compost generated from yard wastes, biosolids, municipal solid waste (MSW), animal manures, and other biodegradable waste by-products, and 3) raw animal manure (with and without bedding). Environmental monitoring has shown elevated nitrate concentration to be widespread in both surface and groundwater, often occurring in regions with concentrated horticultural production. Therefore, the objective of this review was to calculate the nutrient content from organic amendments, since these are not considered nutrient sources. Common organic amendments affect soil bulk density, water-holding capacity, soil structure, soil carbon content, macro- and micronutrients, pH, soluble salts, cation exchange capacity (CEC), and biological properties (microbial biomass). The first step in building a conventional tomato (Solatium lycopersicum) fertility program will be to take a soil sample and send it to a soil laboratory for a nutrient analysis. These results should be compared with the local crop recommendations. Second, select the organic amendments based on local cover crop suitability and availability of compost, raw animal manure, or both. Then, determine the nutrients available from cover crops and other applied organic amendments and use inorganic fertilizer sources to satisfy the crop nutrient requirements not supplied from these other sources. [ABSTRACT FROM AUTHOR]

A renewed interest in sulfur (S) deficiency has occurred because of reductions in atmospheric depositions of S caused by implementation of clean air regulations around the world. In vegetable production systems, other sources of S exist, such as soil S, fertilizers, and irrigation water. While soil testing and fertilizer labels impart information on quantity of S, it is unknown how much S within the irrigation water contributes to the total crop requirement. Two studies were conducted to determine the influence of elemental S fertilization rates and irrigation programs on tomato (Solanum lycopersicum) growth and yield. Irrigation volumes were 3528, 5292, and 7056 gal/acre per day and preplant S rates were 0, 25, 50, 100, 150, and 200 lb/acre. Data showed that neither plant height, leaf greenness, soil pH nor total soil S content was consistently affected by preplant S rates. During both seasons, early marketable fruit weight increased sharply when plots were treated with at least 25 lb/acre of preplant S in comparison with the nontreated control. Early fruit weight of extralarge and all marketable grades increased by 1.5 and 1.7 tons/acre, respectively, with the application of 25 lb/acre of S. There were no early fruit weight differences, regardless of marketable fruit grade, among preplant S rates from 25 to 200 lb/acre. Based upon this result, adding preplant S to the fertilization programs in sandy soils improves tomato yield and fall within the current recommended application range of S (30 lb/acre) for vegetables in Florida. At the same time, irrigation volumes did not consistently influence soil S concentration, soil pH, leaf S concentrations or tomato yield, which suggested that irrigation water with levels of S similar to this location [58 mg⋅L-1 of sulfate (SO4) or 19 mg⋅L¹ of S] may not meet tomato S requirement during a short cropping seasons of 12 weeks, possibly because microbes need longer periods of time to oxidize the current S species in the water to the absorbed SO4 form. [ABSTRACT FROM AUTHOR]

Urban water quality management is becoming an increasingly complex and widespread problem. The long-term viability of aquatic ecosystems draining urban watersheds can be addressed through both regulatory and nutrient and water management initiatives. This review focuses on U.S. regulatory (federal, state, and local) and management (runoff, atmospheric deposition, and wastewater) impacts on urban water quality, specifically emphasizing programs in Florida. Because of rapid population growth in recent decades, and projected increases in the future, appropriate resource management in Florida is essential. Florida enacted storm-water regulations in 1979, before the U.S. Environmental Protection Agency (USEPA) amended the Clean Water Act (CWA) to regulate stormwater discharges. However, in the United States, more research has been conducted on larger structural best management practices (BMPs) (e.g., wet ponds, detention basins, etc.) compared with smaller onsite alternatives (e.g., green roofs, permeable pavements, etc.). For atmospheric deposition, research is needed to investigate processes contributing to enhanced deposition rates. Wastewater (from septic systems, treatment plants, and landfills) management is especially important in urban watersheds. Failing septic systems, elevated nutrient concentrations in discharged effluent, and landfill leachate can all potentially degrade water quality. Proposed numeric nutrient criteria from the USEPA and innovative technologies such as bioreactor landfills are emergent regulatory and management strategies for improved urban water quality. [ABSTRACT FROM AUTHOR]

Organic growers have indicated a need for help with the challenge of nutrient management. To address this challenge, an intensive training program for agricultural educators was convened to study this issue. Through the program, existing soil and compost analysis recommendations were modified to make them more relevant for organic growers; computer-based whole farm nutrient planning tools were evaluated using situations common to organic farms; and educational materials on using organic nutrient sources were developed for grower audiences. Educational workshops, presentations, and farm visits reached 714 growers and publications reached over 2575 people. Survey respondents of the intensive training program rated their ability to help organic growers with nutrient management as 3.50 before and 5.50 (7-point scale, with 7 = excellent) after the sessions. About 1 year later, all survey respondents rated their ability to help growers using organic nutrient sources as excellent or above average. Grower knowledge of using organic nutrient sources improved to 5.92 from 3.92 as a result of a workshop and to 5.62 from 3.89 (7-point scale, with 7 = excellent) after a 1-day class developed by intensive training participants. Methodology used allowed for expansion of individual and collective knowledge of a complicated topic and development of high impact, relevant, and effective educational programming for clientele. [ABSTRACT FROM AUTHOR]

This study examines the relationship between foliar nitrogen:potassium (N:K) ratio and in-shell yield of pecan [Carya illinoinensis (Wangenh.) K.Koch]. Regression analysis of linear and curvilinear relationships between leaflet N:K ratio and in-shell yield identified associations relevant to orchard nutrition management. Analysis revealed that ON (heavy crop) year N:K ratio correlates with ON year yield (r² = -0.69), OFF (light crop) year yield (r² = +0.34), 2-year average yield (r² = -0.52), and difference between ON and OFF year yields (r² = -0.69) below the optimum yield level (less than 1800 kg·ha-1) for southeastern U.S. pecan orchards. Pecan yield therefore appears to be associated with N:K ratio. This study suggests that a decline in pecan yield is associated with high N:K ratios in the ON year, thus meriting further investigation into the relationships of N and K to yield. It is suggested that pecan orchards be managed such that foliage contains a N concentration of 2.5% to 2.9% and a K concentration of 1.3% to 1.5% while maintaining the N:K ratio at ≈2:1 for maximization of pecan yields in the southeastern United States over the long term. [ABSTRACT FROM AUTHOR]

In Massachusetts, cranberry (Vaccinium macrocarpon) bogs were historically developed in existing wetlands and new plantings are now established in mineral soils that are converted into constructed wetlands. To streamline the interaction between cranberry farming and wetlands protection, the state has defined "normal agricultural practices" that are exempt from wetlands regulations under certain circumstances. As part of that process and to qualify for the exemption, farmers are required to have a conservation farm plan and demonstrate the use of best management practices (BMPs) on their farms. The University of Massachusetts Amherst Cranberry Experiment Station (UMass Cranberry Station) was engaged to bring together the U.S. Department of Agriculture, Natural Resource Conservation Service (NRCS) and cranberry industry representatives to define BMPs specific to cranberry farming practices. Initially, the documents were reviewed by scientists and regulators for soundness of science and rigor of environmental protection. A grower committee reviewed the proposed BMPs to determine if the BMPs could be implemented on real farms. The next stage of the project consisted of defining areas where more research was needed to formulate good BMPs. In particular, research projects were initiated to study nitrogen and phosphorus nutrition. This research has become the basis for nutrition BMPs, national cranberry nutrition guidelines, and standards used by NRCS for cranberry nutrient management plans. The cranberry BMP project has continued with a regular cycle of revision and additions based on grower-identified needs for horticultural and environmental guidance. This connection to the growers, along with the regulatory link, accounts for the widespread adoption of BMPs in the cranberry industry. Local NRCS estimates that 75% to 80% of Massachusetts cranberry growers have current conservation farm plans that include BMP implementation. [ABSTRACT FROM AUTHOR]

SUMMARY. The Nutrient Management Act (NMA) established in the province of Ontario in 2002 has prompted a re evaluation of nitrogen (N) management practices. However, N management research in Ontario is currently outdated. The experiment in this 3-year study was designed to establish the yield response of carrot (Daucus carota) to N fertilization on mineral and organic soils and identify the relative yield effects of preplant and residual soil N. In 2002, N was applied at 0%, 50%, 100%, 150%, and 200% of recommended N application rates in Ontario as ammonium nitrate (organic soil: 60 kg⋅ha-1 preplant; mineral soil: 110 kg⋅ha-1 split 66% preplant/33% sidedress). Experimental units were split in half in 2003 and 2004, and N was applied to one half in 2003 and both halves in 2004 to identify the effects of residual N from the previous season on yield. Crop stand, yield, and quality were assessed at harvest, and storability was assessed by placing carrots into cold storage for 6 months. Nitrogen application rate had no effect on the yield, quality, or storability of carrots grown on organic soil. On mineral soil there were no effects of applied N in the first year of the 3-year study. In the second and third year on mineral soil, yield increased in response to increasing N, up to 200% and 91% of the recommended application rate, respectively, based on the regression equations. Yield declined above 91% of the recommended application rate in the third year due to a decrease in stand at higher N application rates. There were no effects of N on carrot quality or storability on mineral soil. On mineral soil, residual N from the 2002 season had more effect on yield at harvest in 2003 than N applied in 2003. This major effect of residual soil N on yield provides an explanation for the lack of yield response to preplant N application in previous studies conducted in temperate regions. These results indicate that there is no single N recommendation that is appropriate for all years on mineral soil. Assessing the availability of N from the soil at different depths at seeding is recommended to determine the need for N application. [ABSTRACT FROM AUTHOR]

The phosphorus index (P-Index) is a risk assessment and management tool to aid in reducing the risk to water quality due to movement of excess phosphorus (P) from fields. An allowable P application rate is specified based on the computed risk. This study focused on the Virginia P-Index. The objectives were to determine the factors to which the P-Index is most sensitive and to determine the factors to which the resulting P application rate recommendations are most sensitive. A differential analysis was used to calculate relative sensitivity for nine baseline scenarios: a low; medium, and high baseline within three different regions of Virginia. Impact of user variability in estimating factor values was evaluated using a probability distribution analysis. The P-Index was most sensitive in the low and medium baseline scenarios to P management factors, including annual application rate, method of fertilizer application, and source availability factor. In high-risk baseline scenarios, the P-Index was most sensitive to transport factors (erosion, runoff, or leaching). User variability had a greater impact on the P-Index and on P application rate recommendations as P risk increased over each of the three regions. The closer a field's P-Index value is to a threshold between P recommendation rate categories, the higher the probability that alternate P application rates will be recommended due to user variability. The results highlight the need for consistent estimation of factor values, particularly the factors to which the P-Index is most sensitive and particularly in the higher-risk situations. [ABSTRACT FROM AUTHOR]

Nutrient management legislation has prompted an evaluation of alternative nitrogen (N) management techniques. SPAD (Soil Plant Analysis Development) chlorophyll and Cardy nitrate (NO3-) meters were evaluated for their potential as tissue nitrogen tests in cabbage (Brassica oleracea var. capitata), onions (Allium cepa), and carrots ( Daucus carota subsp, sativus). Cabbage, carrots, and onions were grown on both organic and mineral soils in Ontario, Canada in 2000 and 2001. Nitrogen was applied at five rates to cabbage and carrots and three rates to onions ranging from 0 to 200% of current provincial recommended N rates. In an additional treatment, 50% of the recommended rate was applied preplant and sidedress N applications of 40 kg.ha-1 (35.7 lb/acre) were applied when SPAD chlorophyll meter readings fell below 95 (2000) and 97% (2001) of the highest N rate treatment. Yields were generally unaffected by N rate, except in cabbage in 2000, suggesting adequate N was present in most treatments. SPAD chlorophyll meter readings were highly variable among soil types, cultivars, and years. Chlorophyll readings reached a plateau in adequately fertilized crops in many instances. Cardy readings were less variable among soil types, cultivars, and years. The relationship between N rate and sap NO3-N concentration was generally linear. The results suggest that the use of a well-fertilized reference plot is most appropriate for the SPA]) meter on these vegetable crops, while the use of region-specific critical NO3-N concentrations was most appropriate for the Cardy NO3- meter. Both meters would be cost advantageous when over 500 samples are tested. The meters were generally easy to use, except for the SPAD meter on carrots. The meters have potential for N management of vegetable crops under Ontario growing conditions. [ABSTRACT FROM AUTHOR]

The recent signing of the NPDES permit regulations and effluent limitations guidelines for CAFO has generated much interest from smaller beef cattle feeding operations for a more cost-effective solution for managing feedlot runoff. A passive runoff control and treatment system was constructed to reduce long-term liquid storage, provide solids separation, and evenly distribute the liquid discharge for grass hay production. The overall objective of this study was to evaluate the effectiveness of this passive system for reducing contaminant discharge. The system effectively reduced the cumulative mass of total and volatile suspended solids and reduced chemical oxygen demand by 80%, 67%, and 59%, respectively. Significant reductions of these constituents in the runoff water as it passed through the system were measured for most precipitation events. No water was measured exiting the vegetative filter strip during the three-year period of this study. Therefore, the discharge water was effectively contained and used for hay crop production. Estimated total nitrogen (TN) load in the discharge water entering the vegetative filter strip was equivalent to or less than the TN removed by the crop. System robustness was demonstrated during feedlot pen renovation when significant reductions in contaminant concentrations were measured for most all precipitation events during that period. [ABSTRACT FROM AUTHOR]