The Short Answer
The full range of factors affecting productivity are rarely assessed. Parts of paddocks, through natural conditions, decline in soil health and productivity. Applying more phosphorus, or more nitrogen is often not a solution and is potentially driving productivity down.
In short, its likely we measure the wrong things, and we don’t measure enough places. We base decisions on insufficient information.
The soil is the engine of wealth creation on a farm. Keeping the natural functions working is directly correlated to potential productivity. Measuring soil for signs of ill health can guide you away from serious financial challenges. Although it can be done inexpensively, monitoring the functioning of the soil is too rarely done. The measures are few in number and easily learned. The interpretation is clear.
Soil varies significantly over short to moderate distances in most farming regions. If you have access to a remote sensing image of your farm, perhaps an NDVI image which shows vegetation vigour, you will see variation across the farm. Remote sensing can help you identify:
where areas of less vigour are located
how big the less vigorous areas are
how much less vigorous plants are in affected areas.
Remote sensing will only reveal the symptoms - plants are not as green as other places; it will not tell you the cause of the reduced vigour in the affected areas. Only going to the areas, and looking for factors affecting the functioning of the plant, such as insects or diseases, or the functioning of the soil will help you improve it.
You may not have access to remote sensing imagery. That’s not a problem. What we recommend is soil sampling using modest cost instruments, and sampling a lot of locations.
Why measure Ill Health?
The primary reason for sampling to check soil health functions is to work on the fundamental soil processes first, at low cost. Fine tuning can come later. Even if you believe you do not have areas of soil ill health, we highly recommend checking by sampling for it. In the best case scenario, you confirm the good health; just as likely though from our experience, you identify emerging problems.
The farm manager should set out to understand if any part of the farm is suffering from low productivity conditions. If you know you have unproductive, low-profitability areas, you know the start point for sampling.
Since the cost of equipment is low, and labour investment not big, it’s wise to sample at least 2 points per ha. That may need to be done in stages.
The Soil Ill Health Benchmarks
If your measured value is worse than a benchmark, one or more soil functions will be performing poorly. This will reduce productivity.
1. Benchmark pH value: less than pH 6. Below 5.5 and down to 4, the soil is in ill health. Above 7.5, there is a problem was well.
2. EC value: EC values greater than 1 decisiemen/100 millisiemens
3. Penetrometer value: above 300 psi before 30 cm depth is reached
4. Soil Texture: very high clay percentages or very high sand percentages
This post was originally much longer, and it continued to grow. It grew too long. More details about each aspect of the Benchmarks will follow in additional posts.
For the moment you could take an outline of your farm blocks and set out a series of sampling locations, aimed at finding where the soil has variation.
For a more strategic design, get in touch with us. The cost will… consistent with our theme here…. be modest.