Farmers see the whole soil picture

Monaro Farming Systems (MFS) hosted its third annual 'soil club' session responding to the growing concerns about managing fertilizer costs.

CSIRO's pasture agronomist Dr Richard Simpson spoke to about 40 Monaro farmers at the Nimmitabel Country Club recently.

The session is part of an initiative begun three years ago to address managing fertilizer costs in the face of rising global fertilizer prices and a bleak forecast that "peak phosphorus" may occur within 25 years.

Dr Simpson said it was imperative that producers use scarce nutrient resources more effectively.

"However, a major issue for our farmers is interpreting the soil nutrition information that is available and translating it into a more efficient and targeted fertilizer program on-farm that can help maintain high stocking rates and productivity, "Dr Simpson said.

With support from NSW Department of Primary Industries agronomist Luke Pope, MFS has built a database of over 650 soil test results, representing 479 paddocks, collected over three years from the three main Monaro soil types based on basalt, granite and shale.

The results show some strong emerging trends.

The basalt soils, as expected generally have high phosphorus (P) fertility but the soil results indicate 19 per cent were below optimum for P, but 82 per cent were below optimum for sulphur (S) with 17 per cent deficient in both P and S.

On granite soils, 61 per cent were below optimum for P but a high proportion (78 per cent) were also low in S, and a quarter may also have low potassium (K) levels. A rather high proportion of granite soils (55 per cent) were potentially deficient in both P and S, with about half of these soils also having low K levels.

On shale soils, soil test results indicated 79 per cent were below optimum for P, 83 per cent below optimum for S and 47 per cent below optimum for K. A relatively high proportion of paddocks had indications of multiple nutrient deficiencies (P and S, or P, K and S).

The results have shown that S fertility is a major issue over all soil types on the Monaro and in some cases, producers may be dealing with multiple nutrient limitations which can make for some difficult fertiliser decisions.

Dr Simpson's main messages included knowing critical target nutrient levels for particular soils, and monitoring this over time by regular testing to guide fertiliser investment decisions.

Understanding the "whole picture" of the soil's nutrient status on the property is important, as one critical element deficiency may be limiting the response to all the other applied nutrients.

Another key message was the importance of matching fertilizer investments with an appropriate level of pasture utilisation to ensure that the financial gains from fertiliser use are fully realised.

This Monaro Farming Systems project, "Targeting fertilizer to fertility" is supported by Landcare Australia and Woolworths.

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