Feeding the world’s growing population
New Zealand’s reputation as a quality food producer is growing.
The Fertiliser Association of New Zealand promotes and encourages responsible and scientifically-based nutrient management.
Understanding and managing soil phosphorus levels (Olsen P) to maintain soil fertility for agricultural production, avoids unnecessary phosphorus use. This helps farm profitability and reduces environmental impacts.
Fertiliser application is one of the largest single operating expenses for most farms. It doesn't make sense to apply fertiliser when it's not required to maintain soil fertility. Soil with excessively high Olsen P levels-especially in 'critical source areas' has the potential to contribute more significantly to phosphorus levels in waterways. This can create adverse environmental effects.
Yearly soil tests
The member companies of the Fertiliser Association (Ravensdown and Ballance Agri-nutrients) use almost 100,000 soil tests each year to support good management practice and appropriate fertiliser recommendations.
Decline in phosphorus use
Phosphorus use has declined since a peak between 2003 to 2005. This reflects the impact of a significant price rise in 2008/09, decreased proportions of land being developed for more intensive agriculture, and economic pressures-particularly for sheep and beef farmers receiving lower returns. The moderate usage also reflects the increasing focus on nutrient budgets. This involves using fertiliser more strategically than ever before, as farmers learn how to maintain productivity while using less.
For total phosphorus use in New Zealand since 1990, see here.
Understanding soil phosphorus fertility across New Zealand
To better understand how soil phosphorus fertility is reflected across New Zealand's production land, the Association analysed routine soil Olsen P test results. This study examined data from approximately 800,000 records from across New Zealand, covering a range of farm systems and soil types collected during the period from 2012 to 2019.
The review helps us to understand the phosphorus status of New Zealand's productive soils.
The target ranges for Olsen P for relevant land-use activities are presented as the coloured band on the figures in this report. More background and detail can be found in our booklet series here.
Map of distribution of sampling
Density of Olsen P measurements across New Zealand using rural and rural-adjacent postcodes.
Table of samples by soil type
Summary of Olsen P records by soil type and region, included in the final data set.