Managing Soils to Achieve Greater Water Use Efficiency

Abstract

Y/T ϭ m/T max [2] Water use efficiency (WUE) represents a given level of biomasswhere Y is the total dry matter production, T is the or grain yield per unit of water used by the crop. With increasing transpiration, m is a coefficient, and T max is the daily concern about the availability of water resources in both irrigated free water evaporation. Water use efficiency is estiand rainfed agriculture, there is renewed interest in trying to develop mated using the total water use (ET) from a crop suran understanding of how WUE can be improved and how farming face, which includes evaporation from soil and plant systems can be modified to be more efficient in water use. This review components because of the difficulty in separating evapand synthesis of the literature is directed toward understanding the oration from transpiration. role of soil management practices for WUE. Soil management prac-Changes in WUE can be manifested through soil mantices affect the processes of evapotranspiration by modifying the available energy, the available water in the soil profile, or the exchange agement practices via the components of the surface rate between the soil and the atmosphere. Plant management pracenergy balance: tices, e.g., the addition of N and P, have an indirect effect on water ET ϭ R n Ϫ G Ϫ H Ϫ P [3] use through the physiological efficiency of the plant. A survey of the literature reveals a large variation in measured WUE across a range where ET is evapotranspiration, R n is net radiation, G of climates, crops, and soil management practices. It is possible to is soil heat flux, H is sensible heat flux, and P is photoincrease WUE by 25 to 40% through soil management practices that synthetic flux. These terms can be expressed in a variety involve tillage. Overall, precipitation use efficiency can be enhanced of units (e.g., W m Ϫ2 and KJ m Ϫ2 s Ϫ1 ). Soil management through adoption of more intensive cropping systems in semiarid practices impact WUE through changes in the energy environments and increased plant populations in more temperate and exchanges (R n , G, and H) and through the plant photohumid environments. Modifying nutrient management practices can synthetic (P) efficiency. These terms will affect the waincrease WUE by 15 to 25%. Water use efficiency can be increased through proper management, and field-scale experiences show that ter balance in the soil within a growing season and across these changes positively affect crop yield.growing seasons. Throughout this review, we will show where soil management practices modify the energy balance components.

Improving water use efficiency of vineyards in semi-arid regions. A review

“…Similarly, Davies et al (2011) showed how, by applying mulches, it could affect more directly WUEc as they can modify soil reserves, minimizing soil evaporative losses and consequently improving water soil infiltration. These results are in agreement with some reviews showing how surface residue management or mulching can improve WUEc by reducing soil evaporation and runoff in other crops (Davies et al 2011;Hatfield et al 2001).…”

Local and Landscape Correlates of Spider Activity Density and Species Richness in Urban Gardens

“…Spiders are sensitive to both microclimate and habitat structure, and mulch may provide suitable burrowing habitat for groundhunting spiders that need specific humidity and temperature conditions (Riechert and Bishop 1990, Uetz 1991, Bell et al 2001. Covering the surface of bare soil with mulch reduces soil water evaporation by decreasing soil temperature, preventing vapor diffusion, absorbing water vapor into the mulch, and reducing wind speed gradients at the soil-atmosphere level (Hatfield et al 2001). The negative correlation of Gnaphosidae activity density with concrete cover and bare soil may be related to the inefficiency of humidity and temperature regulation on these types of ground cover.…”

“…Alternatively, increased tree height may provide more canopy cover to spiders. Canopy cover and mulch can provide temperature and humidity regulation for species-specific habitat requirements (Riechert and Bishop 1990, Hatfield et al 2001, Lin 2010.…”

Nutrients in the nexus

“…Adaptation to these agricultural droughts is critical to increasing and maintaining crop productivity. Soil management practices such as modified tillage, crop residue management, and soil nutrient status have been shown to increase water use efficiency and are a key means of adaption to periods of water stress (Hatfield et al 2001). Nutrient additions increased water use efficiency up to 25 % and conferred significant resilience of yields during Bdrought^years (Sileshi et al 2008).…”