more than 10ha

Integrated Soil Fertility Management (ISFM) refers to a set of agricultural practices that can be applied simultaneously to improve agricultural productivity through increasing soil nutrients and improving crop water use. ISFM includes a broad range of agricultural practices that have all been adapted to local conditions to improve soil nutrients and include the combined application of the following approaches:

1. Utilisation of organic fertilisers such as green manure, compost and crop residues.
2. Application of locally available soil amendment methods, such as lime and biochar.
3. Implementation of techniques like germplasm, agroforestry, crop rotation, intercropping etc.
4. Limited use of inorganic or mineral fertilisers – seen as the last option in ISFM, when other interventions are not achieving optimal results.

ISFM can be successful for most arable farmers and has been known to double productivity and increase farm-level incomes by 20 to 50 percent if implemented correctly. It focuses on a series of practical approaches to sustainable farm productivity through locally available and affordable options for maintaining soil fertility and productivity, and is seen as a viable approach to reduce over-reliance on inorganic fertiliser. ISFM permits short- and long-term increases in productivity of cash crops and food security, and is considered climate smart as the combined ISFM approach maximises fertiliser uptake and sequestration of carbon in soil, allowing sustainable agricultural intensification driven by improved soil structure and fertility.

Soil acidification is a widespread problem across southern Africa, often driven by monocropping with cereals and occurring as a result of erosion, compost decomposition and soil leaching. Applying lime to soil is regarded as a key management practice in agriculture to balance pH, enhancing crop productivity, water penetration and absorption of major nutrients by crops. Most crops grow best in soils with a pH between 6.5 and 6.8. Acidity constrains crop growth below pH levels of 5.5. Agricultural lime is limestone mined as a rock that is crushed into various particle sizes ranging from course to fine particles and can be applied in areas where there is high soil-acidity due to high levels of manganese and iron. Lime texture also determines the speed of absorption in the soil; that is, fine-lime reacts more quickly than more granular lime. However, the use of lime must be managed appropriately to avoid losing other nutrients in the soil. This practice is considered climate smart as it assists with adaptation strategies through improvement of soil fertility, whilst improving productivity at modest application rates, noting that annual application is not recommended.

Soil fertility is one of the most critical factors needs to be maintained so farmers can continue to grow productive and nutritious crops, especially in southern Africa where soils are often fragile and lacking in plant nutrients. Soils are often quickly depleted if mismanaged, further exacerbated by natural biophysical processes such as rain, wind and/or heat. The use of organic fertiliser can help farmers to improve soil fertility, as they improve absorption of water and add nutrients into the soil, drastically improving crop production. Organic fertilisers are plant (crop residues) or animal-based materials, such as green manure, worm mouldings, compost, animal waste, and sewage residues, many of which may be readily available on the farm, or within a farming community. These products are potential counters to inorganic fertilisers - artificially manufactured chemicals (synthetic) mined from mineral deposits comprising minerals such as nitrogen, phosphorus and magnesium - which are often costly when few farmers can access credit needed to sustainably access such materials. Organic fertilisers are considered climate smart as they utilise (recycle) readily available organic materials to feed soil and crops simultaneously as they add nutrients into the soil and condition it, and thus increase productivity and resilience, while inorganic fertilisers add nutrients to the soil only, and are often expensive.