Where to now for nutrient management science?

In 2013 the Ministry for Primary Industries (MPI) commissioned scientists from the Soil and Land Use Alliance (AgResearch, Landcare Research, Plant and Food Research, and Scion) to review research on nutrient management science for the primary sector between 1998 and 2013. The aim was to identify the current state of scientific knowledge, the use and uptake of this knowledge in the sector, and the ‘knowledge frontiers’ and gaps that needed to be filled.

A meta-analysis of the literature found over 1900 articles, which were then grouped by sector (arable, dairy, forestry, horticulture, and pastoral); soil processes such as leaching or mineralisation; soil order; geographic region; and nutrient (nitrogen and phosphorus).

The country was well covered by the research – Canterbury had the highest number of papers, followed by Waikato, Southland, Otago, and Manawatu-Wanganui. Most of the literature, however, focussed on biogeochemical responses with little or no attention to the economic consequences of nutrient management.

Despite the strong focus on soils (1600 references used the term) many papers did not explicitly identify the soil used in the study. Of those that did, gley, allophanic, and pumice soils were the top three (Figure 1). Of the papers where specific soil processes could be identified, leaching was the dominant focus (368 papers) followed by mineralisation (244), then de-nitrification (136), runoff/overland flow (131), and fixation (129).

Science advances have been numerous, and include development and adoption of best management practices – for example farm dairy effluent application and management, and forestry fertiliser management systems; rapid growth in paddock scale and whole-farm system models; development and adoption of a wide range of decision support systems across all sectors based on many field experiments; and inhibitors to manage N cycling and leaching loss.

While science findings are being widely used in practice, we identified areas where implementation of the science needed improvement (Figure 2). Increased translation of science into more useable form, simplification of management software tools, and increasing the numbers of experienced advisors for land managers would be beneficial.

There were some significant science and technology gaps on which future efforts should be focussed to improve nutrient management practice. Three major science opportunities relate to real-time predictions of N availability, manipulation of soil microbial systems, and crop biotechnology for nutrient use efficiency. All new science should be explicitly linked to ‘place’ (region, soil order). On the land, multifunctional and spatially based farm, forest, and orchard models will be needed to address the increasing complexity of land use. These models must better link to economics. Overseer® needs enhancement and validation for more sites and crops, and there is a need to develop metrics to demonstrate the efficiency of NZ’s production systems to consumers.

The report will be published by MPI on its website and used to inform policy development. MPI will also notify key organisations of the report including science organisations, regional councils and research funding bodies such as MBIE.

Reference

Payn TW, Beare M, Shepherd M, Bayne K, Botha N, Collins A, Curtin D, Davis M, Fraser P, Hedley C, Hoogendoorn C, Johnstone P, Lucci G, Parfitt R, Xue J 2013. Nutrient management science – state of knowledge, use and uptake in New Zealand. Ministry for Primary Industries Technical Paper No: 2013/XX. Soil and Land Use Alliance. 439 p.

Tim Payn — SCION Research
P: 07 343 5590 E: tim.payn@scionresearch.co.nz