Potential use of treated wastewater from a cattle operation in the fertigation of organic carrots

The use of treated effluents rich in nutrients and organic matter has intensified in agricultural crops, contributing to the demand for water and fertilizers. The goal of this work was to assess the effects of fertigation with treated dairy cattle wastewater, for the cultivation of carrot (Daucus carota) when applied in four different doses, under field conditions, on nutrient accumulation, productivity, and health quality in the carrot (D. carota). Wastewater from treated cattle (WTC) was treated in a pilot treatment unit (PTU). Cultivation was carried out in two beds, and the WTC applied by drippers. Nitrogen (N) was considered the base element for the dose calculation, and a 100% N dose was equivalent to 150 kg ha-1. WTC doses of 0, 100, 200, and 300% N were evaluated. Productivity was evaluated at 70 and 120 days after sowing, in the aerial part (fresh and dry mass and accumulation of nutrients), in the main roots (fresh and dry mass, accumulation of nutrients, diameter, length, and sanitary quality), and as the total productivity of the two organs. As a result, an increase in productivity was observed for all treatments with WTC and accumulation of Ca and Mg. The roots did not present contamination; therefore, the carrots were fit for human consumption. It was concluded that the application of WTC in organic cultivation of carrots is a viable alternative means of plant fertilization, providing higher root productivity than the national average, reaching 72.6 t ha-1 for a dose of 100% N, without compromising on sanitary quality and is suitable for human and animal consumption.