Reducing Water, Nutrient, Pesticide, and Carbon Footprints and Costs for Drip-Irrigated Vine Crops with Compact Bed Plasticulture

Abstract

Highlights Narrower and taller compact beds (CB) were designed to increase the system efficiency of drip-irrigated plasticulture. CB lowered water, fertilizer, plastic, pesticide, and fuel inputs while maintaining watermelon yield. CB reduced GHG emissions and input costs while increasing input productivity. CB are a synergistic and win-win climate-smart design to increase the sustainability of high-intensity plasticulture. Abstract. Raised bed plasticulture, used globally for producing high-value fruits and vegetables, is a high input and high intensity production system. We show that improved water and nutrient efficiency with reduced material inputs, costs, and carbon footprint is achieved with the use of taller and narrower plastic-mulched compact beds [61×30 (width × height in cm), 61×10, 46×30, and 41×30] compared to the wider and shorter conventional bed [76×20] used for growing watermelon. The primary motivation behind the compact bed design is to improve economic and environmental sustainability by reducing the bed width, to increase the fraction of the bed that is wetted by drip irrigation and to reduce the area of farmland covered under plastic. Compact beds were evaluated at two locations in South Florida with different hydrologic settings, using an ensemble of field data (inputs, plant health, yield, soil moisture, and nutrient levels) and a field-verified hydrologic model (HYDRUS). No reduction in yields was observed with compact beds, indicating no production risk for the growers. Compact beds conserve water and reduce deep percolation losses by 6 cm compared to conventional beds, thereby improving water productivity by 20%. Compact beds require less fertilizer (10%-50%) to maintain the same nutrient (N-P-K) concentrations as those in conventional beds because of smaller soil volumes. Reductions in water and fertilizer inputs provide the environmental benefit of reducing nutrient leaching to groundwater, while reduced impervious area reduces runoff losses. Compact beds reduced input (fertilizer, plastic mulch, pesticide, and diesel) costs of the system by US$720/ha and greenhouse gas emissions by 1630 kg CO2e/ha (9%) compared to conventional plasticulture. The annual cost savings create a win-win for farmers to increase profits and/or invest in conservation measures such as precision irrigation. Compact beds offer a climate change mitigation and adaptation strategy for the plasticulture system for watermelon and other similar cucurbit crops (e.g., cucumber, pumpkin, and zucchini). Keywords: Climate-Smart Agriculture, Economics, Greenhouse Gas Emissions, Nutrient Leaching, Sustainable Design, Water Conservation.