Adaptation to Climate Change with Improved Agricultural Water Management

Adaptation to Climate Change with Improved Agricultural Water Management As the water available for agriculture becomes limiting due to population growth, competition from other water users, drought and water quality degradation, it is important to ensure that every drop of water (either from rainfall and irrigation) counts for crop water use. Evapotranspiration (ET) which is the process by which water is directly loss from soil evaporation (E) and transpiration (T) from the surfaces of plants, is a major component of water use in agriculture. The ability to partition ET into evaporation and transpiration components will help irrigation managers to find ways to improve water use efficiency by increasing transpiration and reducing evaporation.

The Soil and Water Management and Crop Nutrient Section in collaboration with the Chinese Academy of Agricultural Sciences, China Agricultural University and scientists from 12 countries participated in a field campaign recently to evaluate a range of conventional and isotopic techniques to quantify E and T in a maize cropping system. The field campaign took place at the China National Engineering Research Centre for Information Technology in Agriculture (NERTICA), in XiaoTangshan, Beijing, China.

Adaptation to Climate Change with Improved Agricultural Water ManagementThe main criteria for a success story require that activities contribute directly and substantially to the prevention of soil erosion or the reclamation of degraded land, using appropriate and cost-effective approaches and technologies for soil and water conservation.

The campaign was a huge success in bringing not only scientists but also key representatives and isotopic equipment from private international company (Picarro Inc.) together to test not only the state-of-the-art but also novel low-technologies for assessing ET under different irrigation management systems. The conventional techniques tested include Bowen ratio and Eddy covariance instruments for latent and sensible heat fluxes to calculate ET; micro-lysimeters for quantifying evaporation, stem flow and heat ratio gauges for plant transpiration measurements; line quantum sensor and camera imaging for estimating canopy cover of the maize crop; TDR, neutron probe and EnviroSCAN for soil water measurements; and finally laser spectroscopy analyser at multiple height above and below the canopy for water vapour collection and oxygen-18 and deuterium (18 O & 2H) isotopic signatures of the water vapour. This high-tech laser method was also compared with two other vapour trapping systems (a semi-automatic and a low-technology method).

Adaptation to Climate Change with Improved Agricultural Water ManagementThe data is being processed currently and information obtained will form a basis for the best approach to quantify E and T. This will then be tested in a range of countries involved for different crops and irrigation management. The information from this research will be used to test FAO's Aquacrop model for application to different geographic regions. The information will be updated when data processing is completed.