Quantifying the interaction of water and radiation use efficiency under plastic film mulch in winter wheat.

Local natural resources, (e.g., precipitation, solar radiation) are important for developing environmentally and scientifically sound management practices in dryland agroecosystem. Maximizing water use efficiency (WUE) in dryland farming systems remains a challenge. The objectives of this study were to assessing the robustness of radiation use efficiency (RUE) during different periods and investigate the interaction between RUE and WUE from water loss pattern and canopy development during wheat growth under different agricultural practices (non-mulched control, CK; transparent film mulching, TF; and black film mulching, BF) from 2013 to 2016 on the Loess Plateau, Northwest China. Results showed that RUE was mainly improved during post-anthesis under PM treatments. PM treatments contributed to elevated canopy photosynthesis and a delayed RUE peak during the reproductive period. Due to the increased spike number and ratio of plant transpiration to soil evaporation, TF and BF treatments had relatively stable photosynthetic activity relative to the CK treatment even those during dry periods. Initially, no relationship was found between WUE and RUE under the CK treatment. On the other hand, RUE and WUE were positively related in TF and BF treatments following a power function. RUE values increased with WUE rapidly to stabilize at a plateau value of 5.5 g MJ-1 under TF and BF treatments, and thus, the wheat WUE had a higher improvement potential than RUE as it did not have an apparent plateau value. PM treatments enhanced the wheat production by taking full advantage of local solar radiation and precipitation (improving RUE and WUE). This higher use efficiency of resources produced more photoassimilates for wheat than that under the CK management, increased source size (LAI) and sink size (spike number) during wheat growth seasons, and thus increased the final grain yield.

Temporal variability of water footprint for cereal production and its controls in Saskatchewan, Canada.

The water footprint (WF) of crop production is a user-friendly means to analyze the consumption of water resource in agricultural production systems. This study assessed the inter-annual variability of grain yield, protein yield, and their corresponding WFs and determined the major factors influencing the WFs in Saskatchewan of Canada. Both spring wheat and barley showed a significant trend of increasing grain and protein yield from 1965 to 2014, at 194.1 and 179.2kgha-1decade-1 for grain yield (P<0.01) and 18.6 and 17.3kgha-1decade-1 for protein yield, respectively. Coincident with this was that both the grain yield-based and protein yield-based WFs of spring wheat and barley in Saskatchewan showed a downward trend. The grain yield-based WFs ranged from 1.08 to 1.80m3kg-1 for spring wheat, and from 0.90 to 1.38m3kg-1 for barley, whereas the protein yield-based WFs ranged from 7.93 to 10.44m3kg-1 for spring wheat and from 8.14 to 16.47m3kg-1 for barley. The grain yield-based WFs were affected by local precipitation followed by expenses on inputs from farms and the scientific and technological contributions. Under the same protein yield, the protein yield-based WFs tended to be lower in spring wheat than barley. The grain yield-based WFs of cereal crops have large potential for improvement in the future.

A user-friendly modified pore-solid fractal model.

The primary objective of this study was to evaluate a range of calculation points on water retention curves (WRC) instead of the singularity point at air-entry suction in the pore-solid fractal (PSF) model, which additionally considered the hysteresis effect based on the PSF theory. The modified pore-solid fractal (M-PSF) model was tested using 26 soil samples from Yangling on the Loess Plateau in China and 54 soil samples from the Unsaturated Soil Hydraulic Database. The derivation results showed that the M-PSF model is user-friendly and flexible for a wide range of calculation point options. This model theoretically describes the primary differences between the soil moisture desorption and the adsorption processes by the fractal dimensions. The M-PSF model demonstrated good performance particularly at the calculation points corresponding to the suctions from 100 cm to 1000 cm. Furthermore, the M-PSF model, used the fractal dimension of the particle size distribution, exhibited an accepted performance of WRC predictions for different textured soils when the suction values were ≥100 cm. To fully understand the function of hysteresis in the PSF theory, the role of allowable and accessible pores must be examined.