- Optimising nutrient use efficiency (NUE) is now a priority for every farmer as fertilisers of all formulations increase to unprecedented price levels, according to the Agricultural Lime Association (ALA)
With spiralling crop input inflation, maximising the ability of crops to take up and use nutrients to a deliver optimum yields is more important than ever. But according to the ALA to do so requires up-front knowledge of existing soil conditions, beginning with accurate soil testing, analysis and data interpretation.
That helps to identify any deficiencies and where there may be potential savings through better decision making about which nutrients to apply whether in the form of mineral fertiliser or organic manures.
LKAB Minerals’ lead agronomist Mark Tripney says that the first task must be planning to review and correct the basics and that begins with soil pH. With comprehensive soil analysis it’s possible to calculate the base saturation levels of calcium and magnesium.
“Soil structure is enhanced by the application of calcium as it plays an important role in soil aggregation due to the way its ionic charge, size and hydration acts upon the soil colloids, said Mr Tripney. “Soil aggregation or flocculation is the process by which soil colloids and organic matter clump together to form aggregates. It is this aggregation of soil which is commonly referred to as tilth. The aggregation produces pore space which allows the soil to function aerobically, enabling roots to develop without the impedance of compaction and water to drain.
“Calcium also affects numerous biological processes in the soil, including nitrogen transformation processes such as nitrification. This biology is enhanced by the aerobic conditions and aggregation described above, and flourishes when calcium is readily available. This optimised soil state then has a greater ability to sequester carbon and is less prone to denitrification due to the greater stabilisation of soil organic matter.
“An often-overlooked nutrient in soil analysis is magnesium. In certain regions the repeated application of maglime from local sources has resulted in soil structural problems and antagonisms with other nutrients. Conversely in a growing number of areas, a lack of magnesium is becoming an issue. What must be considered before trying to strip this element out of a soil is the calcium-magnesium balance, as magnesium is essential for crop and animal health.
“Magnesium has a key role to play in the formation of chlorophyll and acts as an anchor for Nitrogen in every cell of chloroplast, creating the dark green of a healthy plant. Its major role is in enabling the phloem to transfer products of photosynthesis, sugars down into the roots. Also, as a main component of chlorophyll, magnesium has a key role in the production of ATP (adenosine triphosphate), the energy storehouse of the plant, and it also activates more enzymes in the plant than any other nutrient.”
Therefore, balancing soil pH with a good lime enhances nutrient use efficiency which is key to the profitability of all farming operations. This efficiency is detailed in Fig 2 showing how nutrient utilisation improves when soils are maintained at optimal pH levels with correctional and appropriate liming materials which would initially be either Calcitic or Dolomitic Lime.
If reduced utilisation efficiency figures are used for a soil at pH 6, -11% of applied nitrogen and 48% of phosphorus are potentially wasted from sub-optimal soil pH. This level of financial loss is neither sustainable, nor profitable particularly when a simple low-cost solution remedy with an AgLime Quality Standard (AQS) liming product is available.
“Calcium’s and magnesium role in soil health, plant growth and animal health has long been underestimated. Quality agricultural production has a requirement for a balance of all nutrients. This has not been helped by a focus on the macro elements in farm nutrition budgeting. While the macros may be important for the last step of crop production, they do not improve soil health.
“Achieving the correct balance of cations, calcium being the dominant one, is the route to improving soil health. The cascading benefits ensure that soils function aerobically, healthily, with improved biology, which has reduced GHG emissions and an increased ability to sequester carbon.
“Healthier soils grow crops of better quantity and quality, utilising fertilisers more efficiently and helping further reduce the carbon footprint of the industry. The food produced from these soils is also more nutrient dense and less prone to wastage.
“Calcium and magnesium are nutrients that should not be considered only for pH remediation on a 5-yearly liming cycle. They should be part of farming business and nutrient advisor’s annual nutrient toolkit. Apply little and often to keep the soil in a healthy balance and improve NUE.”
