Phosphorus Requirements & Nutrient Use Efficiency (NUE)

       Review by Paul Storer (Microbiologist), and Burt Naude (Senior Agronomist)

        Western Mineral Fertilisers

Introduction:

In cropping, it is important to remember that nutrients such as Phosphorus (P) must be replaced - as they are removed from soils when grain is harvested (see Table 1).

Research currently being conducted at CSIRO (Sustainable Ecosystems) has found that Nutrient Use Efficiency (NUE) of soluble P in chemical fertiliser applications can be as low as 10-30% in wheat ^1,2,3 .

Biological approaches ^4,5 and farm management practices offer improvements in NUE and the recovery of P + other minerals, and are typically associated with higher yields & increased net $ return. This is reflected in the many field trials comparing WMF Mineral/Microbe biological programs vs Conventional Practice programs (see examples of trial data over page).

Question – is the WMF program “mining soil P”?

WMF Mineral/Microbe biological programs have been tailor made to provide all of the necessary nutrients required by a crop.  Years of soil monitoring has shown that WMF programs have had no detrimental impact on total soil nutrient levels.  Adequate P required for an optimum yield (Table 1) are supplied by the WMF programs (see examples in Table 2 and 3) (WMF Wheat - Applied units P 7.2, Total P removed at harvest  6.7 and WMF Barley - Applied units P 6.3, Total P removed at harvest  4.4 ).

Question – is the WMF program an “expensive P” program?

Soil nutrient availability to plants is not necessarily determined by the amount of the nutrient that is present or applied to the soil (unless it is deficient), but more by how the nutrients are released by the soil to the plant. A key factor to enhancing nutrient availability is by stimulating beneficial soil microbes (see Fig A). 

Tables 2 and 3 also show that the WMF Mineral/Microbe programs utilize P far more efficiently (NUE wheat 48.6% and Barley 53.9% respectively) compared to the Conventional Practice chemical fertiliser programs (NUE wheat 21.9% and Barley 18.1% respectively). 

Table 1: Soil fertility requirements - Nutrients removed (kg) per tonne of production:

Source: National Land and Water Resources Audit Final Report September 2001 APPENDIX 6  ^{Ref 6}

Table 2 - 2008 Wheat Trial (Tincurrin Yipti wheat sown @ 65kg/ha):

• WMF Program  @ 80kg/ha NPK Crop Plus (8%N, 9%P, 4.5%K, 7.6%S, 6.2%Ca, 1.3%Mg, 2%Fe + TE)

with WMF Ag Blend microbial 750g/t seed treatment .

• Conventional Practice Program @ 65kg/ha (14.3%N, 14%P, 9.6%S, 0.04%Zn, 0.01%Mn, 0.3%Ca)

with 30Lt/ha Liq-N (injected) .

• Budget Conventional Program @ 25kg/ha (10.6%N, 21.4%P, 8%S, 0.3% Cu, 0.3%Zn, 0.02%Mn, 0.0009%Mo) with 15kg/ha Urea (down boot) .

Table 3 - 2007 Barley Trial (Gairdner Barley sown @ 70kg/ha ):

• WMF Program  @ 70kg/ha NPK Crop Plus (8%N, 9%P, 4.5%K, 7.6%S, 6.2%Ca, 1.3%Mg, 2%Fe + TE)

with WMF Ag Blend microbial 750g/t seed treatment.

• Conventional Practice Program @ 70kg/ha (11.0%N, 22.8%P, 1.2%S, 0.001%Mo, 0.02%Mn).

Conclusion:

Unbalanced minerals, nutrient deficient soil, nutrient tie-up and low beneficial biological activity can cause poor cropping performance.  WMF Mineral/Microbe programs cost effectively “supplement” soils with mineral nutrients, and at the same time utilize beneficial soil biology to increase Nutrient Use Efficiency ( NUE). The take home message is to adopt cropping programs that manage and increase minerals and beneficial microbes in the soil - allowing for efficient uptake of bio-available nutrients. 

Western Mineral Fertilisers uses a suite of beneficial microbes selected specifically to work with WMF’s biologically friendly and bio-available minerals in our silicate based compound mineral fertilisers.

References:

1. Fillery Ian (2010). Enhancing the capability of the Australian grains industry to improve nutrient use efficiency a nationally co-ordinated systems approach - http://www.grdc.com.au/CSA00021 .
2. Holford ICR (1997). Soil phosphorus, its measurements and its uptake by plants. Australian Journal of Soil Research 35 , 227 – 239. doi: 10.1071/ S96047.
3. Bolland MDA, Gilkes RJ (1998). The chemistry and agronomic effectiveness of phosphate fertilizers. J Crop Prod 1 :139 – 163. doi:10.1300/J144v01n02_07.
4. Xu G-H (2010). Biological approaches to improve nitrogen and phosphorus acquisition and utilization in crops, 15^th International Workshop on Plant Membrane Biology, Adelaide.
5. Smith FA, Christophersen HM, Grace EJ and Smith SE (2010). Nutrient Use Efficiency - Phosphate transport and plant growth in arbuscular mycorrhizal (AM) symbioses: new paradigms, 15^th International Workshop on Plant Membrane Biology, Adelaide.
6. National Land and Water Resources Audit Final Report Sept 2001 APPENDIX 6 - http://www.anra.gov.au/topics/land /pubs/landuse/nutrient-balance.pdf