We can retain and conserve water for crops in the agricultural landscape in a number of ways. By adhering to the provisions of the Code of Good Agricultural Practice, the water retention capacity of soils can be increased. An important role is played here by the correct agricultural use of soil, anti-erosion reclamation, afforestation (creation of vegetated buffer strips), restoration and protection of ecological land, including ponds and wetlands, shaping the appropriate layout of arable fields.
The most effective is a combination of all the methods described below:
- Soil is a natural store of water used by plants. Its ability to retain water depends on its type (e.g. sandy, clay) and to a great extent on its organic matter content. Each percentage of soil organic matter content allows 160 tonnes of plant-available water to be stored per hectare. All measures – agro-fertilisation measures, appropriate crop rotation, catch crops covering the soil and, above all, soil pH regulation through liming, which increases the humus content of the soil and the formation of a cloddy structure – lead to a better water supply for crops.
- The use of agricultural machinery has become indispensable in agriculture, but a side effect of this is the formation of soil compaction, which prevents both the soaking in of rainwater and the water from deeper layers during droughts. The removal of soil compaction improves soil retention and plant water supply also during critical periods.
- Covering the field surface with plants, or plant residues, protects it from excessive drying. Leaving the field surface without a plant cover, especially soil that has been ploughed, leads directly to a loss of moisture from it and provokes wind and water erosion processes.
- Excessively deep cultivation that moves and mixes the soil causes drying and unnecessary, excessive oxygenation, resulting in accelerated decomposition of organic matter. Reducing soil movement and mixing preserves more plant-useful water in the soil.
- Drainage ditches should not only drain water, but – with the construction of levees on them – deliberately and sensibly help to maintain a useful groundwater level. Drainage systems are only intended to drain excessive, unnecessary amounts of rainwater.
- Marshes, mid-field ponds are usually natural creations, allowing water to be stored and stabilising the water level in the soil. They also provide a valuable habitat for many organisms that determine the quality of the environment. The local arrangement of arable fields, grasslands, forests, ecological land, ponds and wetlands is important for water retention.
- Small-scale retention has been neglected for decades. Today, water retention is not only beneficial but also necessary. The primary task of water management in agriculture should be to slow down the outflow of water into watercourses, i.e:
- the storage of rainwater or snowmelt on the site of its generation,
- restriction of rapid water run-off over the land surface – areas of potholes in valleys of field run-off and infiltration ponds and wells for the drainage of rainwater from paved surfaces into the soil,
- economical and targeted management of existing water resources.
In order to counteract adverse developments in water management, the European Union has taken a number of initiatives to conserve Europe’s water resources. One of the most important elements of these activities is the Water Framework Directive and, in agriculture, the Common Agricultural Policy. Member States, including Poland, are launching a number of programmes to support small-scale retention in agricultural areas and beyond.
- Canopy and shrub belts and trees inhibit wind, reduce soil and plant drying and wind and water erosion of the soil, accumulate snow and slow down snowmelt. Reducing field evaporation has a positive effect on reducing water loss from the soil and thus also activates soil micro- and macro-organisms contributing to biodiversity. At the same time, trees and shrubs also provide a habitat for many beneficial organisms. In addition – in the case of soils prone to flooding – trees accelerate drainage, which was one of the reasons for the traditional planting of willows between fields in the Polish countryside.
Anti-erosion drainage, care for the soil, the environment adjacent to the fields is not only the protection of soils and land from erosive degradation and devastation, but at the same time the cheapest way to combat drought, steppe and floods. Any action aimed at slowing and reducing rainwater run-off from areas where it occurs – both agricultural and non-agricultural – improves the overall water supply of the environment and reduces the risk of flooding and waterlogging.