Soil biology The soil must be managed to provide a suitable environment for the microorganisms that are essential to the carbon and nitrogen cycles, and to help maintain soil structure. Equally, this 'biological well-being' of the soil plays an important part in allowing crop plants to develop extensive and efficient root systems which are key to good nutrient use efficiency. The provision and recycling of carbon-containing organic matter to the soil provides the main nutritional substrate for the soil microorganisms. However they also utilize nitrogen and other nutrients, and the downside of their essential activity is the inevitable generation of GHGs. KK Soils should be managed to be well-aerated and to conserve the organic matter necessary for healthy microbial and plant growth. KK Rotations are planned to encourage nutrient and carbon recycling, and to maintain the balance of nutrients and the well-being of organisms in the soil. KK The soil is a living ecosystem and the natural nitrogen and carbon cycles depend upon its healthy activity, which is helped by the return of plant residues to the soil.
Soil chemistry In the context of crop production, the chemistry in the soil is mainly related to its reserves of the essential plant nutrients and the acidity of the soil as measured by pH. It also includes the mineralisation of organic-bound nutrients into the forms in which they are available to plants. Where natural reserves of nutrients are insufficient in the soil, additional nutrients are added and become available to plants in the same forms as are naturally present in the soil. KK Soil nitrogen availability is measured or estimated so that the total supply from different sources - soil, manure and fertilizers - can be calculated and matched as closely as possible with crop requirements. KK Concentrations of available soil reserves of phosphorus, potassium and magnesium should be analyzed every 3 to 5 years depending on crop rotation and soil type. Soil reserves are targeted to be at recommended levels, and nutrients added as required. KK An assessment of likely crop response to sulphur is made according to soil and crop type and geographical location; plant leaf/herbage samples or deep soil analysis can be used as a guide, and sulphur applications made where needed. KK The soil pH should be tested every 3 to 5 years and acidity corrected as necessary using liming materials with known neutralising values. Soil pH is maintained within a suitable range according to soil type and crop rotation to optimize nutrient availability.