Improving water relations in agriculture


What can farmers do to improve water relations in Poland?

The capricious and somewhat delayed spring of 2021 has significantly delayed plant vegetation. Orchardists are concerned about frosts, with many opting to carry out installations and over-crown sprinkler treatments, widely regarded as the surest way to protect buds. Fortunately, the heavy snowfall provided a sufficient supply of water in the soil, it would seem, to use it abundantly for irrigation purposes.

The relatively high water holding capacity of the soils should not cause damage to winter crops and also spring crops if they have been sown correctly, while long-lasting low temperatures have a negative effect on the growth of maize and broad bean plants; delayed sowing of the former increases the risk of drought at a later stage. The example of 2021 shows how unpredictable the weather and its impact on agricultural production is. In previous years, we have experienced an almost yearly occurrence of agricultural drought(2015, 2016, 2018, 2019, 2020) – whereas between 1951 and 1980 it occurred on average every five years. Currently, nearly 40 per cent of our country’s agricultural and forested areas are threatened by extreme and severe drought. This entails significant crop production losses reported by farmers, necessitating the mobilisation of state financial assistance to those affected. In 2015, it amounted to around PLN 0.5 billion, while in 2018 it was already four times as much – just over PLN 2 billion, and in 2019 it will be close to PLN 1.9 billion. In a situation where Poland’s surface and groundwater resources are among the lowest in Europe and agriculture uses around 70% of total renewable water resources, their management should be comprehensive and strategic. In practice, the most important role in water management is played by the catchment users, mainly the farmers themselves, who have a joint and several responsibility in terms of trough retention and water retention for agricultural production as well as other uses. If farmers have such heavy responsibilities, what action should they take to meet them and to feed consumers and themselves? This question takes on particular relevance at a time of increasing expenditure of state budgets in the face of the economic crisis we are facing due to the COVID-19 pandemic.

A systems approach to water management

The EU’s Green Deal commitments and the Union’s drive towards climate neutrality impose a number of environmental requirements on Member States and their citizens. Many farmers may disagree with them and argue that they are too restrictive, damaging production. However, the climate threats they face show that they should already be shifting to a new, rational model of soil and water management and away from the idea of maximising production. They should also engage in local cooperation to develop joint solutions to facilitate water collection and conservation. The environmental and climatic threats we face today, which are hitting agriculture itself, are too serious to ignore the resources at our disposal – soil, water availability and quality, biodiversity and air. The way out of the predicament is a systemic approach to sustainable ecosystem management in rural areas.

Farmers are users of productive space and affect directly or indirectly unproductive elements of agroecosystems (balks, woodlots, wastelands) as well as other ecosystems (surface water, peatlands, grasslands, forests etc.). All elements of the agricultural landscape play a specific role in organic matter and nutrient cycles and water balance. In spite of the technological and genetic progress in recent decades, which has significantly improved productivity efficiency, the associated changes in the structure of agricultural land and intensification of production (increase in the level of use of fertilisers and pesticides) have led to species simplification of crops in the form of predominance of cereals and maize, and partly rape. In the conditions of Poland, we are also dealing with a significant decrease in the number of animals (resulting from the lack of availability of natural fertilisers) or a significant concentration of livestock in certain regions (most often of high-producing breeds) and a decrease in agricultural land cultivated in a traditional manner. The result is a decline in the resilience and sustainability of agricultural ecosystems, exacerbated by ongoing climate change and the extent to which natural resources are used, in effect reducing yield growth and stability. The availability of water for crops is correlated with the availability of organic matter, phosphorus and potassium in the soil and the way the soil is cultivated and protected. Attempts to restore production potential in monocultures often end in failure and require costly and lengthy application of treatments to improve soil structure and fertility. Another problem for Poland’s rural areas is the excessive acceleration of water run-off due to the regulation of rivers and drainage ditches (the latter about 320,000 km2), which currently perform mainly drainage functions. Pressure on resources is also caused by irrigation – between 2010 and 2016 there was an increase of nearly 200% in the area irrigated.

Water resources

Everything starts at the source. Renewable water resources in Poland’s river basins come from rainfall. Most of it evaporates, with the remainder (about 28%) flowing out through river systems. Only about 20% of the total precipitation infiltrates into groundwater, recharging it. We generally use the first groundwater layer, which renews itself over a period of about three years. As a consequence of climate change, the matter is becoming even more complicated – there is more rapid rainfall, which the soil cannot absorb, so it almost all drains away via rivers; the frequency of rainfall is shifting towards the winter months; in addition, the growing season is lengthening (by 20-30 days in the last 50 years), increasing the predominance of evaporation over precipitation, which is characteristic of our country (the Climatic Water Balance, in the context of drought, defines the difference between precipitation and potential evaporation from plants and soil (evapotranspiration). Unfortunately, the possibility of collecting valuable rainwater in local catchments is very limited in Poland. There is a lack of information on the potential of small on-farm retention reservoirs, which have significantly higher utility for agriculture than large dam reservoirs.

What should be done to counter water losses in agriculture?

Collect water and save it. Local measures, adapted to the conditions of the river catchment and the landscape, are the most effective. Slowing down water run-off within small catchments and retaining it on the surface or in the ground is known as low retention. A systems approach to water management requires the trust and cooperation of all land users and increased awareness among farmers about sustainable water management.

Storing water in a watercourse or ditch with the use of levees and weirs significantly increases the resources on adjacent land, the groundwater level is raised and the size of the disposable resource is increased. Farmers with meadows in floodplains will soon be able to benefit from the introduction of compensation for their flooding for retention purposes. Agricultural irrigation should use appropriately adjusted doses depending on soil type and plant needs, and special attention should be paid to significant water savings by using continuous soil moisture monitoring in the root zone with a set of sensors and using IT decision support systems.

The most important thing for crop production is the availability of water in the soil itself. Caring for the soil, for its structure, increases the level of soil retention. Water retention is determined by the granulometric composition (texture) of the soil, soil porosity, organic matter content, ground cover and the current availability of water in the soil. In agricultural practice, we can only influence the improvement of soil water-air relations (optimum porosity and soil texture) and protection against evaporation. In the first case, we achieve a direct effect by loosening the soil, preventing mineralisation (oxidation) of humus and erosion, using natural, organic fertilisers and rationalising mineral fertilisation. Protecting against water evaporation requires a complex set of measures, starting with breaking the capillary rise of water (e.g. by no-till), through practices that affect the water balance at field level (maintaining permanent soil cover with healthy vegetation), as well as at the scale of the agricultural catchment (introducing mid-field planting or agro-forestry systems that improve the microclimate and organic matter content of the soil; together with baulks and sodded filter strips, they also significantly reduce surface water runoff).

An enriched crop rotation with appropriate plant selection in terms of habitat suitability, soil organic matter enrichment capacity and resistance to disease threats, pests and water stress is crucial. Mention should be made of the need to adapt sowing dates to the availability of water accumulated in the soil during winter and to reduce the amount of seed sown. The balanced use of natural and organic fertilisers (especially the incorporation and ploughing of faba bean plants) provides organic matter and nutrients especially nitrogen, increasing the nutritional status of plants and resistance to stress. In both cases, the environmental impact can be negative (for example, the ploughing of green manures can increase the risk of nitrogen (N) and phosphorus (P) leaching), so it is very important to adapt agrotechnology to weather and soil conditions (dose, timing, location). In the conditions of Poland (about 50% of the soils of agricultural land are characterised by a very acid and acid reaction), the effectiveness of organic fertilisers will also depend on the optimisation of the soil reaction, i.e. their liming. Fertilisation with potassium significantly increases the available water reserve in the soil, especially in cereal crops. The increasing effectiveness of water absorbers (hydrogels) is noteworthy; products based on potassium compounds appear to be the most promising for water binding. On large areas of the field, it is worth investing in precision fertilisation with a parallel driving system, which is particularly beneficial on compact soils to promote root development. On textured and erosion-prone areas, ribbon (contour) cultivation may work well. However, of all cultivation systems, organic farming is the most effective way of conserving soil water in the long term. Research by IUNG has shown that compared to conventional, integrated and monoculture systems, the organic carbon content remains at the highest level, while the soil infiltration rate with winter wheat cultivation in the organic system was about four times higher than in the conventional system. The results of scientific work indicate that the most effective in protecting against water evaporation and reducing surface runoff on arable soils is the maintenance of cover (catch crops, catch crops, mulch, mulching). It is estimated that ground cover in combination with no-till increases water infiltration by 12-46%.

Water security cannot be considered without taking animal husbandry into account, especially in the context of its industrialisation and concentration. Animal production is the largest consumer of water in the food production process. Livestock farmers should keep in mind not only the current water requirements of the different technological groups of animals, but also the possibility of storing water in case of drought. The use of rainwater from the roofs of farm facilities and the recovery of water from technological processes are recommended. Controlling animal grazing and stocking rates protects the soil and vegetation and increases water infiltration. For watering the animals, the construction of ponds in the grazing area and the use of gravity-fed or pumped water supply systems are recommended. Water abstraction from deep wells should only be used in exceptional cases.

Summarising the above, two slogans seem particularly important for farmers to remember: the motto “Leave the rain where it fell” and the old Polish proverb “Then one respects water when it is scarce in the well”.

You will be able to find more information in the Living Earth Coalition’s publication “Water in Agriculture” and in the soon-to-be available Code of Good Water Practices in Agriculture, edited by IUNG-PIB staff in Puławy.

Author: Robert Borek

Department of Bioeconomy and Systems Analysis, Institute of Soil Science and Plant Cultivation – National Research Institute (IUNG-PIB) in Puławy

The text was written as part of the project „Hydrozagadka – jak wygrać z suszą?”