Phosphorus fertility on sheep and beef farms
Phosphorus (P) fertility on hill country sheep and beef farms is not always optimal. As a result, farm productivity potential can be compromised.
There is an abundance of scientific evidence showing that investment in P fertiliser, where required and applied correctly, can increase and/or maintain pasture quality, production, soil biota and microbiological activity.
Olsen P is the standard soil measure of plant available P used in New Zealand and provides the basis of capital and maintenance P fertiliser application decisions. Increasing low Olsen P soil test values with capital applications of P fertiliser or maintaining Olsen P levels with maintenance levels of P fertiliser is an essential management decision.
When considering capital and/or maintenance applications of P fertiliser, consider the relative optimum of soil fertility rather than the optimum soil fertility that provides near-maximum pasture production.
At the relative optimum, soil test levels differ considerably depending on soil type, climate, topography, and aspect. For example, sheep and beef farms grow different amounts of pasture depending on stocking rate and animal production. Only the highly stocked finishing farms with favourable soils, climate and terrain achieve near-maximum pasture production. That is, need optimum soil fertility.
Many sheep and beef farms are breeding operations, with some finishing livestock, and have varying proportions of hill country that have limitations to pasture growth other than soil fertility. These farms are typically stocked at relatively lower rates and will not achieve near-maximum pasture production. In these cases, relative optimal Olsen P soil test ranges are lower than a highly stocked finishing operation.
Whether increasing pasture production and/or just maintaining it, applications of P fertiliser to hill country sheep and beef farms should be considered a valuable business investment. However, this must be coupled with sound advice on what are the relative optimum and the fertiliser products and quantity required to achieve this.
Contact your local PGG Wrightson Technical Field Representative for advice and assistance planning a fertiliser programme for your farm.
