Integrating poultry improves soil health and vegetable yield in organic, cover-cropped system

Abstract

Organic vegetable growers depend on organic fertilizer sources and must optimize on-farm nutrient cycling. Integrating poultry, such as chickens, in an organic vegetable rotation offers an opportunity to cycle unharvested plant material into nutrient-rich manure. Additionally, poultry consumption of weeds and insects can add additional agroecosystem services. While cover cropping is a common practice in organic production, integrating livestock is not, but it may further enhance on-farm synergies and improve soil health. Our objectives were to evaluate the impact of integrating organic vegetables and poultry (Gallus gallus domesticus) on vegetable yield, weed and cover crop biomass, and several measures of soil health, including: plant-available nutrients, soil bulk density, water infiltration rate, aggregate stability, earthworm abundance, and microbial biomass. We explored these effects over three years with three rotation treatments: a no-poultry control (vegetable-vegetable-cover crop, Control), vegetable-poultry-cover crop (V-P-CC), and vegetable-cover crop-poultry (V-CC-P). The treatments had no effect on aggregate stability and microbial biomass. However, integrating poultry consistently increased many essential plant macro- and micro-nutrients. For instance, the two poultry rotations increased spring plant-available N by 88 %, P by 30 % and K by 29 %, compared to Control. Integrating poultry increased infiltration rate, measured as field saturated hydraulic conductivity, by 108 % in V-P-CC and 148 % in V-CC-P, compared to Control. However, only V-CC-P increased earthworm abundance compared to Control, by 109 %. These increases in plant-available nutrients and soil health likely contributed to increased leaf lettuce yields in V-P-CC (+96 %) and V-CC-P (+86 %) relative to Control. Our results show that integrating poultry with organic vegetable production can have many benefits to soil health and crop productivity, and points to even greater benefits when the poultry are integrated after a summer cover crop.