Fertigation With Agro-residue-Based Paper Mill Effluent on a High-Yield Spinach Variety.

Disposal of paper mill effluent is a problem. A study was undertaken to determine the potential of an agro-residue-based paper mill effluent as an alternative of irrigation water on spinach (Spinacia oleraceaL), var. Hybrid-7. The study was conducted during the rainy (July to October) and winter (November to February) seasons of 2011 and 2012. Doses of paper mill effluent of 5%, 10%, 25%, 50%, 75%, and 100% were used along with bore well water (control). Paper mill effluent increased electrical conductivity (EC), pH, organic carbon (OC), total Kjeldahl nitrogen (TKN), calcium (Ca2+), iron (Fe2+), potassium (K+), magnesium (Mg2+), sodium (Na+), phosphate (PO43−), sulfate (SO42−), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn) of soil in both seasons. There were no changes in soil water-holding capacity and bulk density due to fertigation. Agronomic performance ofS. oleraceaincreased due to treatment with 5% to 25% paper mill effluent and decreased due to treatment with 50 to 100% paper mill effluent compared to the control in both seasons. Crude proteins, crude fiber, and total carbohydrates were highest due to treatment with 25% paper mill effluent in both seasons. Heavy metal concentrations increased due to treatment with all concentrations of paper mill effluent in both seasons. The order of contamination factor of heavy metals was Cr > Cd > Mn = Cu = Zn for soil and Cr = Cd ≥ Mn > Cu = Zn forS. oleraceaaveraged over seasons after fertigation. Paper mill effluent can be used as a biofertigant after appropriate dilution to improve yield ofS. oleracea. [ABSTRACT FROM AUTHOR]