Performing Department
Department of Plant and Environmental Sciences
Non Technical Summary
Managing soil fertility, crop nutrition, and weed and soil-borne diseases are some of the biggest challenges that organic vegetable growers face. One of the difficulties in managing plant nutrition in organic production systems occurs due to a mismatch between the nutrient release rate of organic fertilizers and peak plant nutrient demand. For organic vegetable growers, this mismatch means nutrient release from organic fertilizers that often cannot supply enough nutrients to support periods of rapid crop growth, resulting in the loss of yield or decreased crop quality. Further, the aggressive nature of weeds and diseases and limited means for their management in organic systems, results in substantial loss of marketable crop yield worldwide up to 45-95% and 21.5% yield losses to weeds and diseases, respectively. All these factors make organic vegetable systems less productive and highly variable from one growing season to another. The proposed project aims to improve the yield and profitability of organic vegetable production by developing organic fertilizer formulations using new organic materials from manure processing and rendered materials, with higher nutrient use efficiency and for weed and soil-borne disease management. The proposed project will develop new fertilizer formulations using new manured-based organic products and rendered materials as a base matrix and will employ various natural amendments to increase the retention of mineralized nutrients in the soil for crop uptake for a longer duration, thus facilitating higher nutrient use efficiency. Further, the project team will pair the new fertilizer formulations with novel plasticulture to utilize the carbon in the standardized organic fertilizers for controlling the weeds and soil-borne diseases in organic vegetable crops through anaerobic soil disinfestation (soil disinfestation by creating anaerobic conditions with organic carbon amendments and irrigation under plastic mulch). The project team proposes to produce a pelletized material of standardized fertilizer formulations and evaluate the impact of new fertilizer formulations + novel plastic mulch on crop nutrient use efficiency, soil health, nitrogen losses, weed and soil-borne disease management, and economic feasibility of using new fertilizer formulations and novel plasticulture. The project team will further promote the adoption of new fertilizer formulations and management practices by communicating the research results and guidelines to stakeholders, scientists, and industry professionals in the southeastern and other regions of the US, through extensive education, extension, and outreach program.
Animal Health Component
0%
Research Effort Categories
Basic
50%
Applied
30%
Developmental
20%
Goals / Objectives
Organic vegetable farming is a holistic production/management system that promotes and enhances agroecosystem health, including biodiversity, biological cycles, and soil biological activity. Major challenges that plague organic vegetable production include a lack of knowledge and limited means to manage soil fertility, weed pressure, and pest outbreaks, which contribute to lower crop yields in organic production systems compared to conventional production systems. Despite scrupulous attempts to improve crop nutrition (through organic amendments), weed (through manual, mechanical, and cultural weeding), and disease (crop rotation, etc.) management, these areas remain among the biggest reasons for low yields in organic production systems. The proposed project aims to utilize the various natural amendments to tailor the nutrient release rate from new organic materials created through manure processing and rendered materials to match the nutrient release rate of organic materials to that of crop nutrient uptake rate and for anaerobic soil disinfestation. Thelong-term goalof the proposed project is to improve the productivity and profitability of organic vegetable crops by developing organic fertilizer formulations from manure products and rendered materials, for higher nutrient use efficiency and anaerobic soil disinfestation for weed and soil-borne disease management. Our integrated research and extension (outreach) activities will lead to effective management strategies to increase domestic organic vegetable production and profitability.The specific objectives of the proposed project are:Prepare and evaluatethe new organic materials-based and rendered materials-based fertilizer formulations for higher retention of net mineralized nutrients in soils for a longer duration by combining them with various natural agricultural amendments and horticultural oils.Fine-tuningthe regulated new organic materials-based and rendered materials-based fertilizer formulations:For maximizing the anaerobic soil disinfestation by combining with novel plasticulture materials.For nutrient release rate under plastic mulch and in the presence of plants.Evaluatethe impact of standardized organic materials-based fertilizer formulations (and their application rate) + novel plastic mulch cover:On crop N and P use efficiency, soil health, and environmental loss of nutrients.For anaerobic soil disinfestation, for its ability to reduce the incidence and population density of weeds and severity of soil-borne disease in organic vegetables grown under plastic mulch.Conducta cost-return analysis of new fertilizer formulations in combination with novel plastic mulch as compared to currently used farmer management practices.Promotingthe adoption of new fertilizer formulations and management practices by communicating research results and guidelines to stakeholders, scientists, and industry professionals in the southeastern and other regions of the US, through extensive education, extension, and outreach program.
Project Methods
We will conduct laboratory, greenhouse, field and on-farm experiments to prepare, standardize and evaluate new manure product-based and rendered material-based organic fertilizer formulations. The lab incubation studies will be conducted to prepare and evaluate the new manure product-based and rendered material-based fertilizer formulations for higher retention of net mineralized nutrients in soils for a longer duration by combining them with various natural agricultural amendments and horticultural oils.Lab incubationswill be conducted in plastic cups using Barnwell loamy sand and Yonges loamy fine sand, soils collected from the certified organic fields of Clemson University, SC. The experiment will be structured as a completely randomized design with five replications. For the mineralization studies, 250 g of dried soil will be amended with 0, 11.5, and 23 mg of nitrogen, through new manure-based materials and rendered materials. This equates to 0, 100, and 200 kg of nitrogen/ha, which is sufficient to meet the nutrient demand of most vegetable crops. We will mix different naturalamendments at different rates (0, 3, and 5% of nitrogen application rate) with each rate of new manure-based materials and rendered materials in a factorial design. Five replicates per treatment will be harvested at weekly intervals for up to 84 days, days and used to quantify the carbon, nitrogen, and phosphorus mineralization patterns, potential ammonification and nitrification, and soil microbiological health. All data will be subjected to analysis of variance using JMP software. Means will be separated according to Tukey's HSD test (α= 0.05). Thegreenhouse studieswill be conducted to maximize the anaerobic soil disinfestation potential of standardized new manure product-based and rendered material-based formulations (from lab studies) by pairing with novel plastic mulch cover (black, bio-degradable, and UV reactive) and capturing the influence of novel plastic mulch and plants on mineralization of nutrients. For the greenhouse studies, we will test the 100% recommended rates of nitrogen application (in conventional production systems). For anaerobic soil disinfestation, native soil weed seed bank of the certified organic field soils will be considered and fusarium wilt culture will be applied to soils in pots. After the organic formulations and fusarium wilt culture mixing in the soil and plastic mulch application, the soil will be water-saturated, and pots will be kept in the greenhouse (mimicking the regional spring weather) for 6 weeks prior to watermelon transplanting. Two watermelon plants will be transplanted in 5-gallon containers. The soil moisture content in the pots will be monitored continuously using TDR probes and will be maintained between 60-70% water holding capacity. The containers prepared as above, but without the plants, will be used to elucidate the effect of plants on nutrient mineralization. All data will be subjected to analysis of variance using JMP. Means will be separated according to Tukey's HSD test (α= 0.05). The different observations on nutrient mineralization rates, plant nutrient uptake, weed management, and fusarium wilt disease severity index in watermelon will be collected. Thefield experimentswill be conducted to evaluate the impact of standardized manure product-basedand rendered materials-basedformulations + novel plastic mulch cover: on nitrogen and phosphorus use efficiency of watermelon crop, soil health, and environmental loss of nutrients;for anaerobic soil disinfestation, for its ability to reduce the incidence and population density of weeds and severity of soil-borne disease in organic vegetables grown under plastic mulch. The field studies will be conducted at Edisto Research and Education Center, Blackville, SC, and also at the United States Vegetable Laboratory, Charleston, SC on certified organic fields and grower fields. We plan to test 10-15 promising treatments in split plot design with a combination of standardized organic fertilizer formulations + plastic mulch [main plot: standard farmer practices, manure product-based fertilizer formulation + novel plastic mulch (1), rendered materials-based + novel plastic mulch (1)] and their application rates as sub-plots, replicated four times on a plot size of 24×30 ft2(3 rows with 10 plants in each row). The field experiments will be conducted for evaluating the dual purpose of the standardized organic fertilizer formulations, novel plasticulture, and their application rates for nutrient management and anaerobic soil disinfestation- for weed and soil-borne disease management. The watermelon nursery will be planted with the cultivarValor. The impact of different treatments on watermelon fruit yield, fruit quality, nutrient use efficiency, soil microbial diversity and abundance, nutrient leaching losses, weed management, and fusarium wilt disease severity index will be evaluated. To evaluate the economic feasibility of new fertilizer formulations and novel plasticulture,partial budget analysisand change in production profits will be calculated. Partial budget analysis is a widely used analytical method practiced by farm owners and managers to estimate the net economic effects of changes in production systems. It is a standard method to compare the financial impacts of changes in various production practices, such as nutrient management, weed management, soil anaerobic disinfestation, and planting methods. The analysis will reveal how profits are expected to change with the adoption of alternative farming practices. Labor, cost, and time savings will also be included in the partial analysis, as appropriate. For example: additional cost of- new fertilizer formulations, natural amendments, novel plasticulture logistic costs; additional income of higher quantity, size & quality (grades), and price, will be taken into consideration while calculating the partial budget. Additional data related to standard production costs, quality, prices, and market will also be cited from USDA, National Agricultural Statistical Service for South Carolina. If needed, to collect any supplementary economic data, we will plan an online survey of major producers in South Carolina in consultation with the Clemson Cooperative Extension.