a grip on soil fertility
DESCRIPTION
High soil fertilty = high food production Establish soil fertlity with soil tests With only one soil test > 20 soil characteristics can be measured. Based on a single soil test fertilzation recommendations are given, but also additional information like a soil organic matter balance, and a water retention curve is given to farmers and their extension services.TRANSCRIPT
Arjan ReijneveldAugust 27, 2013
A grip on soil fertility
Dr. Arjan ReijneveldThe Netherlands
Soil fertility
Soil fertility = nutrient and water supplying and retaining capacity of the soil
Soil fertility is, since beginning of 20th century, established by soil tests
Soil tests:
until now
Soil tests until now
For every soil characteristic (N, S, P, K,…) a different method
- Time consuming chemical analysis
- Expensive
- Mostly based on knowledge of the 1960th - 1970th
Soil tests: nowadays
Soil tests: nowadays
Soil in a jar of glass
Analysed with near infra red method (NIR)
In every soil sample > 20 soil characteristics
> 20 soil characteristics
Among others: N-total
S-total
P-total and P saturation
Ca-, Mg-, K-, and Na-CEC
Plant available Ca and K
Soil texture (clay, silt, sand)
pH
CEC, Total C
Soil Organic Matter (SOM) Soil Organic Carbon (SOC)
CaCO3
From soil test to report
Those > 20 soil characteristics of the soil test are transformed to a report
On the report
● Fertilization recommendations (nutrients)● Among others Phosphorus
● Extra information● CEC
● Organic matter balance
● Soil structure
● Water retention curve
● Soil type
Example II
Example III
Example IV
Example I
Example IPhosphorus
Phoshporus (P)
Recommendations based on:● Plant Available P as well as on● Soil supplying capacity
Improved root development: better uptake of nutrients and less drought sensitive
Example IICEC
CEC and yield potential
13
CEC can be improved by:
Effective CEC improved by pH improvements
CEC improved by input organic matter- Crop residues
- Compost
- Animal manure
- Green manuring
- Organic fertilizer
Example IIIOrganic matter
Soil organic matter (SOM)
2.9 % SOM
mineralisation
Input through crop residues
Shortage, to be filled in with animal manure, compost, green manuring….
Not only a measurement but also information about maintaining soil organic matter content (balance)
17
Improved SOM status
Improved soil workability
Less drought sensitve
Example IVWater
retention curve
Water retention curve
Plant available water
Wilting point
Field capacity
Water retention curve
Information about: Which fields are most drought sensitiveHow much mm of water can be irrigated
Too much irrigation ● water will leach to deeper soil layers● nutrients will leach
Finally
Sampling sites
NIR stations could be established everywhere (worldwide)
Higher soil fertility = higher production
With NIR technique much insight in soil fertilty
More insight can be used to optimise - Production (yield)- Product quality - Water use- Prudent use of minerals
Results of soil tests should be discussed with famers and extension services (advisors) to fully exploit its added value
In conclusion
Soil tests can contribute to
● Profitable farming
● Feeding a steadily increasing world population
FAO, 2012
Thank you
Arjan [email protected]