July 23, 2015
Understanding our most precious asset – the soil
A far better understanding of soil variations than most sampling systems permit is essential to improving arable cropping performance and resilience, argues Agrii head of Decision Support Services, John Lord.
“Yield mapping can identify the major in-field variations that bear much of the responsibility for the performance plateau we’ve seen in commercial crop production over the past 10-15 years,” he stressed. “But it tells us nothing about the key limiting factors causing these variations. Nor how we can best and most cost-effectively address them.
“To do this we need to really understand our most precious asset – the soil – and its incredible spatial variability. For which a traditional sample per hectare is nowhere near enough in most cases. And more samples taken more widely are also of little value unless they adequately reflect the variation of the soil in question.”
In theory, Mr Lord explains that in most cases around 200 samples/ha would be required on a simple grid-based system to be sure of obtaining a sufficiently accurate picture of soil variation. But as this would be prohibitively expensive, an alternative approach is required to balance resolution and affordability.
The greatest resolution can be obtained at the least expense by GPS-based sampling across field zones previously identified as broadly similar through electrical conductivity scanning or by satellite imagery. This approach allows sampling to be targeted to give the best possible understanding of soil variations across each field.
“As well as sufficient resolution through ‘intelligent sampling’ we need the right degree of accuracy in our soil analyses,” he insisted. “Laboratory laser texture analysis gives us a precise breakdown of particle size distribution for each field zone with major implications for fertilisation, seed rate, liming strategy, compaction risk, slug and black-grass threats and spring N responsiveness, amongst other management essentials.
Alongside such greater soil understanding, Mr Lord sees equally exciting cropping improvement opportunities from better use of a growing range of other performance and environmental data.
“Yield mapping and other historic information effectively integrated over several years offers us the best basis for future planning,” he noted. “Soil probes providing up-to-the minute information on moisture levels and remote sensing devices capturing real-time intelligence on crop growth and condition before they become evident to the naked eye will really improve our timeliness. And increasingly sophisticated disease and pest forecasting from local weather station data will do much to ensure the most cost-effective targeting of our crop protection efforts.
“However sophisticated we become in doing this, though, everything will depend on having sufficient understanding of our soils, so we can manage them to the best and most sustainable effect. More than anything else, investing in this understanding has to be the key to future faming success.”