Agricultural practices and drought resistance: EcoFoodSystem delivers its first results

In November 2020, a new long-term, structuring experiment was set up on 27 hectares of land at the Gembloux Agro-Bio Tech experimental farm. As the plots enter their second growing season, marked by significant dry spells in spring (driest March since 1883), the experiment reveals its first results in terms of soil drying dynamics and phytosanitary debt.

EcoFoodSystem

Four innovative long-term rotations (8 years), adapted to the silty regions of the Hesbaye (Belgium), are tested, in 15 x 80 meter plots. These rotations, developed using joint crop and diet optimization tools, are tested to see if co-evolutions between contrasting farming and food systems are coherent or compete with each other in terms of food security, agronomy and environmental objectives. The systems tested will include:

1. The reference or "off-farm" rotation: a "regionally optimized flows" hypothesis, following the useful agricultural areas (UAA). Food systems and agriculture are open to import and export, and the animal is introduced via the flows of agricultural co-products and manure. This system is tested in two variants: with the use of herbicide on the one hand, and with zero phyto on the other.
2. The ICLS (Integrated Crop Livestock System) or "agroecology" rotation: a "locally optimized flows" hypothesis, where crops are produced to meet a "healthy and sustainable" diet as defined by the EAT-Lancet commission and where the animal (particularly the ruminant) is used as a functional tool for weed and pest management via grazing of temporary grasslands and intercrops. As in the previous hypothesis, the animal is introduced via the flow of agricultural co-products and manure. This system is tested in zero phyto.
3. The Vegan rotation: a "zero flow" hypothesis, simulating agriculture in a society where livestock would no longer be tolerated. In this system, also conducted in zero phyto, there will be no production for animals and no use of manure.

In the trial, the rotations are tested in two time frames and thus start in year 1 (T1) or 5 (T2).

Around the test plots, an ecological mesh is installed to increase biodiversity and associated ecosystem services: hedges, flower strips, strips hosting messicolous plants, presence of trees (agroforestry trial already in place). Measurements are carried out each year to determine the stability (resistance and resilience) and to determine the impact of the rotations on water, microbiota and soil composition, biodiversity, weeds, pests and crop protection agents.

For more information, we invite you to read our article dedicated to the implementation of the experiment.

Agriculture Is Life For Water Quality (AIL4WQ)

Within this vast institutional trial, managed by the CARE Agriculture is life (AIL) in charge of basic measurements on soil and crop science, all Gembloux Agro-Bio Tech researchers are invited to submit projects that will allow them to go further in their respective disciplines. It is in this context that the AIL4Water Quality project was born.

The approach was initiated by the dual observation that:

• Knowledge of the fate of pesticides in soil is limited. The necessary data are the sorption and degradation characteristics of the molecules. They are currently provided by the manufacturers. However, when included in the model and confronted with field observations, it is obvious that these parameters must be adjusted. A better knowledge of the fate of the most impacting substances for water quality is essential to improve their management.
• conventional production systems show their limits in terms of reducing diffuse pollution. Marginal adjustments in conventional systems only produce marginal effects. It is becoming necessary to develop innovative production systems that could potentially generate radical changes in the environmental impacts of agricultural practices.

AIL4WQ proposes to address these two aspects through

• Hydrological monitoring of the 3 innovative EcoFoodSystem production systems
• Monitoring of pesticide (and nitrate) transfer on soil columns under controlled conditions

The trial was therefore equipped with temperature, water potential, and water content probes (at 30 cm, 60 cm, and 90 cm depth) as well as soil solution sampling plates (under the roots, at 1.50 m).

First results

For their second cropping season, all plots were planted with winter wheat. Initially, similar moisture levels and a slow decrease in moisture content were observed for all plots in the early spring of 2022 (see "moisture content at 30 cm" graph below for example). In a second phase, after April 10, there is a more rapid decrease in this measure and a marked differentiation between plots. This decrease in water content can be explained by different factors : the increase in temperature (following a period of dryness in March, the driest since 1883) and an accelerated growth of winter wheat (requiring larger quantities of water), from mid-April.

If the experiment reveals its first results in terms of soil drying dynamics, it is advisable to remain cautious about the analyses that are made of these data (second year of monitoring, with a very different meteorological situation in 2021). Despite this remark, the water content of the soil at different depths and the water potential seem to vary according to several factors, so certain dynamics can already be noted.

• Previous crop: ICLS plots ("T1 agroecology") on which corn was grown in year one retain less water than plots on which camelina ("T1 vegan") or beet ("T1 off-soil phyto") was grown. This could be explained by the existence of different root systems and/or an earlier harvest. Similarly, we note that plots in which rapeseed was grown in year 1 (T2 plots, all rotations) have a lower overall water retention than T1 plots in which beet, camelina and maize were grown. Thus, the dynamics of dewatering seem to be influenced by the previous crop.
• Tillage: plots with less tillage, using smaller farm machinery, have better conservation of their soil structure and can retain water better. Thus, in this experiment, plots covered with camelina in year 1 ("T1 vegan") appear to be more resistant to drought risks than plots on which beets were grown ("T1 off-till phyto").
• Use of phytosanitary products: plots receiving phytosanitary treatment logically have fewer weeds, but these weeds tend to pump water from the soil. As a result, T1 plots consume less water than untreated plots (T1 off-soil phytosanitary), but with a risk for water quality.

These observations show us that the hydrodynamic properties of the soil are influenced by agricultural practices and that the various previous crops lead to different soil water retention behaviors. After two years of experimentation, one particularly wet, the other with a tendency to drought (on a planned 8-year rotation), monitoring must continue in order to better understand the resilience factors of the production systems studied.

The project AIL4WQ is realized in collaboration with the Agriculture Is Life platform of Gembloux Agro-Bio Tech, the CRA-W, Greenotec and Protect'eau and is financed by the Société Publique de Gestion de l'Eau (SPGE)