Today, ZLTO the southern agriculture and horticulture organisation in the Netherlands announced that the spring drought will increase food prices in the Netherlands. There is a rainfall deficit currently of 60 mm since 1st of April. Many of the top soils are too dry for the germination of crops. Water boards have installed bans on groundwater abstraction for irrigation in the South of the Netherlands (1). This is leading to a situation that I know from Kenya, where farmers and pastoralists generally wait for the rains. Now farmers in my backyard are waiting for the rains. Why is this happening and what can be done?

Early rainfall deficits seem to be occurring more frequently. I recall spring droughts from 2019, 2018 and 2017 (2). Strangely, The Netherlands is still perceived as a green country. The reason is that there is sufficient rainfall for the vegetation in the country. So why do we not have sufficient water for our crops now?

It is not that there is not enough water throughout the year. It is that the water was there before but it has already left the places where it is needed. As example, if we redo the calculation of the rainfall deficit for the period of 1st of January this year until end of April, there is no deficit. Actually we would have a 13 mm surplus. (If the entire autumn and winter period is included, this surplus would of course be higher).

In other words, the water was there before but now it is not. So where did it go? Most of the rain that fell since the 1st of January was rapidly transported out of the agricultural fields through a system of ditches, canals, streams and rivers to the sea. In the Netherlands, we are not yet capable enough to hold on to the valuable water. The sad result is that farmers are waiting for rains and Dutch food security is threatened.

So what can we do? Right now, the water is not there so the only thing we can do is hope for rains. However, we can start to be better prepared for the years to come as it is likely that we will have more of these early spring rainfall deficits.

Move to full year monthly rainfall deficit/suplus graphs, or even better to full water balances

A first simple step would to start creating a full year rainfall deficit or surplus graphs instead of only the ones from 1st of April to end of April. This would give a fast and easy to understand overview of the total water availability and consumption throughout the year. Actually, it would be better to create monthly full water balances to inform our water decision making on where we want the water to be, at what time and how to best do make that happen.

Embed green water management in water management approaches

Secondly, since we are talking about rain, we should start embedding green water management in our water management approaches. (Green water is root zone soil moisture that originates from rain). Our water boards are mostly equipped to manage surface and ground water (blue water). As a result, green water management is in its infancy. The water balance above could incorporate a green water component as root zone soil moisture.

Restore green water stocks

Thirdly, the early spring droughts have to do with changes in the water cycle in the Netherlands. Recently, Wang-Erlandsson et al. (2022) addressed green water as planetary boundary and highlighted that this planetary boundary was already transgressed. This means that too little of the rain water is stored in the root zones of our soils. Why is green water so important? Green water is root zone soil moisture from rains. It is water that is available to plants that can be transpired in the process of plant growth or evaporated from the soil surface. The transpiration and evaporation increases the amount of water vapour in the air. Using a bit of common sense and imagination, you can understand that when this water vapour condenses it will create clouds and rain.

The transformation of natural landscapes to agricultural landscapes has generated two outcomes that impact the water cycle. The first is that agricultural landscapes generally have periods where no vegetation is present on the soil. This not only reduces transpiration and the amount of water vapour in the air, it also creates higher tempuratures on land surfaces and the air above them. With higher temperature water vapour has less chance to condensate. Cloud formation and rainfall is thereby reduced.

Also, agriculture has changed the nature of soils. Generally, under agriculture, soils have less organic matter and biodiversity, the soil ecosystem is less complex and soil structure is changed. The result is that less water can be held in agricultural soils. This means that rain will more quickly runn off and/or drain. As a result, the total soil water content of the soil after rain - the green water stock - is lower then in natural soils. As we have seen this has implications for the water cycle and rains.

There is a real opportunity for farmers to work on restoring the green water stocks in their soils. And, interestingly, the new EU Common Agricultural Policy (3) through the focus on specific environmental measures could support these activities.

Keep blue water in the system as long as possible

Water managers are increasingly working to maintain more blue water stocks in the system during periods of rainfall surpluses. In the South of the Netherlands, the shallow ground water levels are generally fluctuating with surface water levels. Part of the water requirement for agriculture in the early spring could be covered using the shallow ground water sources if they are maintained at a higher level. Often it is the same farmers that do not like higher ground water levels in the early season as it creates difficulty for land preparation activities. Through this in a way they are creating their own water problem later in the season. As a thought experiment, if farmers would allow a generally higher ground water level this could ease at least part of 60 mm deficit that is occuring now. Together with restored green water stocks in the soil this would be enough to ease the drought problems that are faced now.

Of course it is not easy to do all this, it requires open minds, open communication, collaboration and creativity of all involved, as well as the courage to move out of habitual practices into innovative ones. We would love to hear your views and are ready to contribute with our expertise and skills.

References:

(1) (https://www.aaenmaas.nl/actueel/nieuws/2022/april/tijdelijk-verbod-gebruik-grondwater/)

(2) https://www.knmi.nl/nederland-nu/klimatologie/geografische-overzichten/historisch-neerslagtekort

(3) https://ec.europa.eu/info/food-farming-fisheries/key-policies/common-agricultural-policy/new-cap-2023-27_en