Plastic mulching in agriculture. Trading short-term agronomic benefits for long-term soil degradation?

Drought is a major environmental stress threatening wheat productivity worldwide. Global climate models predict changed precipitation patterns with frequent episodes of drought. Although drought impedes wheat performance at all growth stages, it is more critical during the flowering and grain-filling phases (terminal drought) and results in substantial yield losses. The severity and duration of the stress determine the extent of the yield loss. The principal reasons for these losses are reduced rates of net photosynthesis owing to metabolic limitations—oxidative damage to chloroplasts and stomatal closure—and poor grain set and development. A comprehensive understanding of the impact of terminal drought is critical for improving drought resistance in wheat, with marker-assisted selection being increasingly employed in breeding for this resistance. The limited success of molecular breeding and physiological strategies suggests a more holistic approach, including interaction of drought with other stresses a...

Drought Stress in Wheat during Flowering and Grain-filling Periods

Agriculture consumes more than two thirds of the total freshwater of the planet. This issue causes substantial conflict in freshwater allocation between agriculture and other economic sectors. Regulated deficit irrigation (RDI) is key technology because it helps to improve water use efficiency. Nonetheless, there is a lack of understanding of the mechanisms with which plants respond to RDI. In particular, little is known about how RDI might increase crop production while reducing the amount of irrigation water in real-world agriculture. In this review, we found that RDI is largely implemented through three approaches: (1) growth stage-based deficit irrigation, (2) partial root-zone irrigation, and (3) subsurface dripper irrigation. Among these, partial root-zone irrigation is the most popular and effective because many field crops and some woody crops can save irrigation water up to 20 to 30 % without or with a minimal impact on crop yield. Improved water use efficiency with RDI is mainly due to the following: (1) enhanced guard cell signal transduction network that decreases transpiration water loss, (2) optimized stomatal control that improves the photosynthesis to transpiration ratio, and (3) decreased evaporative surface areas with partial root-zone irrigation that reduces soil evaporation. The mechanisms involved in the plant response to RDI-induced water stress include the morphological traits, e.g., increased root to shoot ratio and improved nutrient uptake and recovery; physiological traits, e.g., stomatal closure, decreased leaf respiration, and maintained photosynthesis; and biochemical traits, e.g., increased signaling molecules and enhanced antioxidation enzymatic activity.

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Regulated deficit irrigation for crop production under drought stress. A review

The global temperature has been increasing over the years due to climate change that, directly or indirectly, affects water and energy consumptions in the agriculture sector. The application of mulching practices reduces soil evaporation, conserves soil moisture, suppresses weed growth, controls soil structure and temperature, influences soil micro-organisms, and is aesthetically pleasing. This study has reviewed 189 published research papers, which described the effects of various mulching materials and methods on soil and environment that influence crop productivity. This paper describes the extent of influence of different mulching materials and methods on the hydrothermal environment of soils. It is imperative to know the processes that control soil environments under various mulching conditions and the effects of mulching materials on crop yield, productivity and water use efficiency. These issues of mulching are the prime concerns of this review study. Plastic mulching materials have a greater importance than the organic ones to control soil environment and increase crop yield. But, the organic mulching materials are inexpensive and environment friendly. The selection of an appropriate mulching material is, however, guided by crop type, crop management practices and climatic conditions. Future research is needed on the effects of low-cost biodegradable mulching materials on microclimate modifications, soil biota, soil fertility, crop growth and crop yields.

Recent advances in mulching materials and methods for modifying soil environment

Effects of plastic mulching and plastic residue on agricultural production: A meta-analysis

Increasing food demands by a growing human population require substantial increases in crop productivity. In rain-fed arid and semiarid areas where the water supply is limited, an increase in the precipitation use efficiency (PUE) is the key to reach this goal. This chapter examines the scientific basis of a ridge-furrow mulching system (RF system) for increasing PUE, and summarizes the effects of this system on crop performance, microclimates, soil attributes, and environmental sustainability. Studies have shown that using crop straw, plastic film, or gravel–sand materials to mulch the soil surface significantly reduces the evaporation of soil moisture, increases water availability to crop plants, and decreases soil erosion caused by wind and water. Plastic mulching increases topsoil temperature during cool spring, promoting plant growth; during hot summer, straw mulching can moderate soil temperature, preventing the topsoil from reaching temperatures that inhibit plant growth. Ridge furrows with plastic mulching on the ridges and crop straw covering the furrows channel water to the furrows, and enhance soil water infiltration and water availability to the crop. Microclimates under mulched ridges and furrows favor soil microbial activity, increase soil biodiversity, and improve environmental benefits. The effectiveness of ridge-furrow systems is reflected in increased crop yields (20–180%) compared with that of the conventional-flat planting. Although more research is required to document physiochemical strengths, technique details and potential drawbacks, and more importantly to define long-term sustainability, we strongly suggest that RF systems are an innovative approach for increasing crop water availability, improving soil productivity, and enhancing food security for arid and semiarid rain-fed areas.

Ridge-Furrow Mulching Systems—An Innovative Technique for Boosting Crop Productivity in Semiarid Rain-Fed Environments

Oilseed flax is one of the most important oil crops in China. With the improvement of people's living standards and the deepening knowledge of the nutritional value of oilseed flax, the demand and economic value of oilseed flax are increasing, and the cultivated area in China is expanding. However, the grain yield of oilseed flax is lower than other oil crops. It varies significantly from year to year, combined with a lower degree of mechanization, which has greatly limited the healthy development of the flax industry. Some of the effects of agronomic measures on productivity and water use efficiency of oilseed flax are reviewed in this paper. The major agronomic strategies for the productivity of oilseed flax were presented based on fertilization, plant density, irrigation, cropping pattern and weed control. Future research should investigate the effect of silicon and potassium fertilizers on the mechanism of lodging resistance of oilseed flax, the effects of diversified cropping systems (strip intercropping and crop rotation) on high and stable productivity and efficient utilization of resources. 

Agronomic cultivation measures on productivity of oilseed flax: A review

Oilseed flax (Linum usitatissimum L.) is an important oil crop, and the SIMPLE model is a very effective tool to simulate crop production. In this study, to adapt the SIMPLE model for the overall improvement of flax production and yield, three promising cultivars of North China—Longya Hybrid No. 1, Baxuan No. 3 and Zhangya No. 2—were selected. Experiments were conducted in Dingxi, Wulanchabu, Datong and Zhangjiakou in Northern China from 2016 to 2020. The SIMPLE model was first calibrated and then evaluated for the simulation of flax growth and development and grain yield and biomass. A base temperature of 5 °C was used for phenology, with optimum temperatures from 16 to 20 °C for the third pair of true leaves to unfolded to the budding stage, and from 20 to 25 °C for the flowering stage. In the results, the average simulated value of aboveground biomass in Dingxi was 8772 kg ha−1, with a root mean square error (RMSE) of 1239 kg ha−1 (d-index = 0.69). The simulations were also good in the other three sites according to a comparison of the predicted and observed biomasses (RMSE 135 kg ha−1 and d-index 0.90 at Zhangjiakou, RMSE 280 kg ha−1 and d-index 0.95 at Wulanchabu, and RMSE 140 kg ha−1 and d-index 0.97 at Datong). Flax grain yield was well simulated compared with the observed values, with a RMSE of 55 kg ha−1 and a d-index of 0.96 for Dingxi, a RMSE of 63 kg ha−1 and a d-index of 0.93 for Wulanchabu, and a RMSE of 5 kg ha−1 and a d-index of 0.97 for Zhangjiakou, whereas the yield was somewhat underestimated for Datong (RMSE of 176 kg ha−1 and d-index of 0.91). Overall, the SIMPLE model provided satisfactory predictions under different environments and management. Care should be taken when transferring the SIMPLE-Flax model to other environments, as vernalization and day-length sensitivity are not included in this model.

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Jun-Yi Niu

Papers

Ridge-Furrow Mulching Systems—An Innovative Technique for Boosting Crop Productivity in Semiarid Rain-Fed Environments

Agronomic cultivation measures on productivity of oilseed flax: A review

Adaptation of the SIMPLE Model to Oilseed Flax (Linum usitatissimum L.) for Arid and Semi-Arid Environments