Phophorus and nitrogen leaching losses during turf establishment

Abstract

Concerns over water quality have led to required removal of 50 % of dairy manure phosphorus (P) from the impaired Bosque River Watershed. Application of composted dairy manure (CDM) to sod and moving P off the watershed with sod has prompted a study using box lysimeters to determine NO3--N and P leaching from transplanted sod grown with CDM and inorganic fertilizer as well as sprigs top-dressed with CDM. Treatments were applied to lysimeters filled with a silica sand medium. Three leaching events were imposed, leaching 0.07 to 0.09 % of the total P applied and 0.09 to 1.43 % of total N applied. Concentrations of P in leachate averaged 0.04 to 0.25 mg L-1. Top-dressed CDM on sprigs leached statistically greater amounts of NO3--N than both transplanted sod treatments and greater P than the fertilizer grown sod. After the third leaching event, all treatments received an additional application of P, 100 kg ha-1 as CDM for manure-grown sod and sprigs, 50 kg ha-1 as triple superphosphate for fertilizer-grown sod. An additional three leachings were imposed. Top-dressed sprigs and transplanted sod leached similar amounts of P following the additional P application. Applied nutrients appeared to stay mainly in the sod layer and in the sand medium just below the sod layer. Top-dressed CDM appears to exhibit greater leaching losses of NO3--N than transplanted manure-grown sod and greater N and P losses than transplanted fertilizer grown sod.