A more trustworthy P recommendation by implementing the intensity, buffering capacity, quantity concept into agricultural practice.

1. A more trustworthy
P recommendation
by implementing the
intensity,
buffering capacity,
quantity concept
into agricultural practice
A r j a n R e i j n e v e ld

2. Introduction

3. Introduction (back then)
● P fertilization recommendations for agricultural
crops are based on soil tests from ~ 1900 onwards
● Already at that time, it was suggested that two or
more soil P test would give more insight in soil
processes and improve recommendations
● However, mostly for reason of costs, this was not
implemented

4. Introduction (nowadays)
●Modern soil analysis methods (costs decreased)
●Optimal crop yield and quality increasingly important
(world food)
●Environmental protection has become a topic
●P resources are exhaustible
●Legislative restrictions for P-fertilization
●Farmers value soil P tests, doubt the current
recommendations, and are interested in improved
allotment of P

5. So, there seems room for a more
trustworthy P recommendation
5

6. Material
&
Methods

7. Material
Literature: Throughout 20th century
combination of soil tests was promoted
● P intensity= plant available P
● P buffering capacity = capacity to
replenish plant available P when
P is taken up by crops
● P quantity = total capacity for
P replenishment

8. 8
Direct
Available
Nutrients
Plant Available
ElementsSoil Stock
Total
Soil Stock
Methods P-total or P-oxalate P-Al or P-CAL or P-Olsen P-CaCl2 P-water
Metaphor Basement Kitchen Table Plate
Kg P ha-1 3400 545 4.7 2.5
Soil Quantity Soil Intensity

9. Method
Stepwise introduction
i) Scientific research to further test the concept
ii) From 2004 onwards on all reports (all farmers)
P intensity P-CaCl2
P capacity P-Al/P-CaCl2
P quantity P-Al
iii) Validation in field experiments (grass, maize, potatoes)
iv) Making it an ‘official’ recommendation (>2010)

10. Results

11. Results: variation of P intensity within a
P quantity category
0 1 2 3 4 5 6 7 8 9 10 11 12
0 - 10
10 - 20
20 - 30
30 - 40
40 - 50
50 - 60
60 -70
70 - 80
>80
0,71
1,07
1,4
2,3
3,3
4,12
5,2
7,85
8,56
P intensity, P-CaCl2 mg P kg-1
Pquantity;P-AlmgP2O5100g-1
percentile, 10 - 50%
percentile, 50 - 90%

12. Results (P recommendation)
● On average: lower P recommendations (15 kg P2O5 ha-1)
● Different allotment over fields
● In general: lower recommendations when
soil P status is low, but small recommendation
even when soil P status is higher

13. Discussion

14. Discussion: improvements
Buffering capacity is represented by ratio P-Al/P-CaCl2
Recommendations could be improved by
measuring Fe, Al, and Ca on routine basis
(to establish Fe-P, Al-P, and Ca-P binding)
Risk of leaching can be established

15. Discussion: international (P-Olsen)
A lot of variation in plant available P within P-Al,
but also within P-Olsen, and P-CAL

16. Discussion: other nutrients
Concept can also be used
for other nutrients:
For example:
K plant available (K-CaCl2)
K soil stock (K-CEC)

17. Soil P status of a soil is established by one soil P test
Government in the Netherlands has the intention
the use quantity and intensity characteristics to
classify soils and establish P applications from
2015 onwards.
Discussion: legislation

18. Conclusion

19. Conclusion
Improved allotment of P
useful for food, farmer and environment
19

20. Thank you all!
Questions?
Arjan Reijneveld Arjan.Reijneveld@blgg.nl
Gerard Abbink
Martijn van Oostrum
Debby v. Rotterdam Debby.vanRotterdam@nmi-agro.nl
Wim Bussink Wim.Bussink@nmi-agro.nl