4. Preserving water resources

Water is tapped by agriculture to ensure food security for the world’s growing population.A constant flow of water through plants, with ‘water-for-carbon’ exchange in stomata, is involved in crop production. Every kilogramme of biomass produced by a crop requires between 200 and 1 000 l of water depending on the species and cropping strategy. However, the prospective population growth and climate change will herald an increase in pressure on water resources for agriculture. These issues especially concern Mediterranean and tropical regions. The population rise is accompanied by increased demand for water for nonagricultural uses, leading to between-use competition for water, particularly during the summer when water resources are low and needs are high. Besides global warming, which increases crop water needs, climate model projections indicate a trend towards increasing droughts and extreme storms where water is lost by runoff. In addition to this quantitative aspect (‘save the resource’) is a qualitative aspect (‘save the quality of the resource’) because inputs used in agriculture (fertilizers, pesticides) are a major source of surface water and groundwater quality degradation.

Agriculture is thus faced with a triple challenge—to produce more while preserving the quality of water resources and coping with their scarcity. Water savings could be achieved by optimizing crop functioning in terms of production and sustainability, via agronomic and genetic strategies, under limited water supply conditions. The goal is to breed genotypes that will perform well under water deficit conditions, and to develop cultivation techniques and cropping systems that promote infiltration and reduce evaporation.

In order to preserve water quality, it is essential to gain insight into surface water contamination processes and design cropping systems that will reduce the use of polluting inputs and their seepage into groundwater and streams.

The agricultural research platform in Montpellier (France) addresses all of these issues through teams whose research focuses are interlinked on a continuous scale ranging from crop plant physiology to the hydrological functioning of catchments, including cropping systems on plot, farm and territorial scales. Modelling is pivotal to these research studies, which are based on a consistent multiscale metrological approach. Ecophysiological models (based on physiological processes) are combined with crop models that describe biophysical flows within plots to predict the potential impact of adaptive traits on yield under different climatic conditions. These predictions can then guide the selection of plants that are highly efficient with respect to water usage. Cropping system functioning is modelled with the ultimate aim of designing and testing highly productive crop management sequences and cropping systems that do not deplete water resources. Emphasis is placed on the use of biological diversity of crop species, management of crop associations and sequences and soil conservation techniques. By modelling the hydrological functioning of agrosystems, the impact of these cropping strategies on the functioning of catchments could be quantified in terms of water use and resource contamination. New sustainable management methods, on the basis of these findings, could then be designed for rural areas.

Agronomy research expertise

• Research projects
• Research units and teams involved

Drought tolerance of maize crops: selecting genotypes for different agroclimatic conditions

Improving drought tolerance in crops is hampered by the contradictory aims of maintaining production in drought conditions and reducing the yield loss risk. Depending on the climatic scenario, maintaining leaf growth under water shortage conditions may be an advantage (photosynthesis remains high) or a drawback (risk of plant death by faster soil water depletion). (...)

---

Impact of global changes on water and agricultural productivity in the Mediterranean region

Agriculture has a vital socioeconomic development role in northern and southern Mediterranean regions. This sector is known to be particularly sensitive to current and future global changes. LISAH is contributing to the development of decision support tools and adaptation strategies for the benefit of agrosystems affected by these changes. Three major initiatives (...)

---

Beninese farmers’ perceptions of climate change and their adaptation strategies

This research is focused on the adaptation of family agriculture to climate change. Based on the assumption that changes can best be described by those exposed to them, a survey of farmers was carried to determine their perceptions of the phenomenon and consequences on the environment and their daily lives. Technical adaptations adopted to deal with changes were (...)

---

Persistent soil pollution and health safety of horticultural pesticides–a case study of chlordecone in the West Indies

Chlordecone is an organochlorine pesticide that was used from 1971 to 1993 in the West Indies. This molecule is stable and continues to persist in the environment, resulting in chronic contamination of the environment and certain crops. Little is known about the dispersion mechanisms of this pesticide, which is highly adsorbed on soils with elevated organic matter (...)

---

Impact of coffee-based agroforestry systems on water quality and in reducing erosion phenomena

Cropping systems have been widely assessed for their production capacity and impacts on natural resources. Agroforestry systems (AFS), in which several plant species are intercropped in a plot, including trees, can successfully meet these two challenges. Generally AFS, especially those based on tree crops like coffee, are very widespread in Central America. Many (...)

---

Hydrological functioning on plot and catchment scales in tropical environments–a case study of banana

Ignorance of the main mechanisms controlling the fate of pesticides used in tropical environments is partly responsible for environmental problems in the West Indies and most banana-growing areas worldwide. As part of a study to assess the fate of pesticides in volcanic tropical environmental conditions, environmental degradation which could be potentially induced (...)

---

Assessing the hydrological impacts of cropping practices in Mediterranean environments

In catchments in which cropland accounts for a major share of the area, cropping practices are an important factor with respect to increasing risks of soil erosion and diffuse pesticide pollution of water. These risks are assessed on two complementary scales, i.e. cropping practice implementation (crop plot) and integration of their effects (catchment).

On

 (...)

---

DMCs and geographical extension of conventional cropland areas into dry humid tropical regions

The geographical range within which crops are conventionally grown should be extended into soil-climate areas under harsher conditions so as to be able to produce more and better while meeting the new market demand. Three complementary ecosystem functions that occur under DMC are essential. First, enhanced water resource management, by reducing runoff and evaporation. (...)

This example was not published on the file in July 2010.

---

Research units and teams involved in "Preserving water resources"

Click on the title to see the web site	Member institutes and partners	Scientists number	Director	Description
UMR LEPSE : Ecophysiology Laboratory of Plants under Environmental Stress	Inra, Montpellier SupAgro	15	Bertrand Muller	See the description
UMR LISAH : Laboratory for the Study of Interactions between Soil, Agrosystems and Water Systems (in French)	Inra, IRD, Montpellier SupAgro	23	Jérôme Molenat	See the description
UMR SYSTEM : Tropical and Mediterranean Cropping System Functioning and Management The unit generates knowledge and tools for use in assessing, steering and developing cropping systems.	Cirad, Inra, Montpellier SupAgro	20	Christian Gary	See the description
UPR AIDA : Agro-ecology and Sustainable Intensification of Annual Crops The Annual Cropping Systems (SCA) and Conservation Agriculture and Engineering (SIA) Research Units were merged to form this new unit as of 1 January 2014.	Cirad	56	Eric Scopel	See the description
UPR SIA -->AIDA : Conservation Agriculture and Engineering -->Agro-ecology and Sustainable Intensification of Annual Crops The Annual Cropping Systems (SCA) and Conservation Agriculture and Engineering (SIA) Research Units were merged to form this new unit as of 1 January 2014.	Cirad	13		See the description
UPR GECO : Banana, Plantain and Pineapple Cropping Systems Although export fruit crops are a major source of jobs and currency, they are now often barely viable, in agronomic, economic or social terms. These fruit monocultures often cause pollution and impoverish the environment. The markets are increasingly competitive and consumers increasingly demanding.	Cirad	22	Jean-Michel Risède	See the description