New Zealand Journal of Agricultural Research abstracts
Growth and chemical composition of legume-based pasture irrigated with
dairy farm effluent
N. S. Bolan
D. J. Horne
L. D. Currie
Institute of Natural Resources
Massey University
Palmerston North
New Zealand
Abstract Land treatment of farm effluent is becoming
popular in many countries because this practice is considered less harmful
to surface water and groundwater resources. However, the supply of large
quantities of selective nutrients, such as nitrogen (N) and potassium (K),
through effluent irrigation could affect the nutrient balance and the botanical
composition of crops and pasture. The aim of the project was to investigate
the influence of farm effluent irrigation on the growth and chemical composition
of legume-based pasture through a field experiment conducted at Massey University
Dairy Unit, New Zealand. Three levels of effluent irrigation with N loading
rates of 0, 150, and 200 kg ha–1 were applied. Effluent irrigation
at these rates also provided 0, 256, and 342 kg K ha–1. The effluent
was irrigated either in the presence or absence of calcium (Ca—as gypsum),
and magnesium (Mg—as epsom salt) addition. The effluent irrigation was applied
once a month and the trial continued for 6 months. The dry matter (DM) yield,
botanical composition, and nutrient concentration in the pasture were measured
1 month after each effluent irrigation. The pasture DM yield increased with
increasing rate of effluent application. The DM response (kg DM kg–1
N applied) ranged from 4.1 to 7.2, slightly less than the values obtained
for fertiliser N. The N and K concentrations in the pasture increased with
increasing levels of effluent irrigation. Calcium and Mg fertiliser application
had no effect on either pasture yield or the concentration of N or K in pasture.
In the absence of Ca and Mg fertiliser application, the concentration of
Ca and Mg in pasture decreased with increasing effluent irrigation. Application
of Ca and Mg fertiliser increased the concentration of these elements in
pasture at all levels of effluent application. Excessive uptake of K by pasture
is likely to cause Ca and Mg deficiencies in grazing animals, leading to
milk fever and grass staggers
Keywords botanical composition; DCAD; dairy cattle;
farm effluent; GSI; nutrients; pasture
A03022; Received 17 April 2003; accepted 1 December 2003; online publication
date 26 February 2004
New Zealand Journal of Agricultural Research, 2004, Vol. 47: 85–93
0028–8233/04/4701–0085 © The Royal Society of New Zealand 2004
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