Plastics in soil: Analytical methods and possible sources

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

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

Effects on soil temperature, moisture, and maize yield of cultivation with ridge and furrow mulching in the rainfed area of the Loess Plateau, China

The current cropping system of conventional tillage and stubble removal in the northwestern Loess Plateau of China is known to decrease the water use efficiency and crop yield because of soil infertile and degradation. To determine the effects of straw incorporation on the soil fertility and crop yield, we conducted experiments in semiarid areas of southern Ningxia for 4 years (2007–2010). Four treatments were tested: (i) no straw incorporation (CK); (ii) incorporation of maize straw at a low rate of 4500 kg ha −1 (L); (iii) incorporation of maize straw at a medium rate of 9000 kg ha −1 (M); and (iv) incorporation of maize straw at a high rate of 13500 kg ha −1 (H). After straw incorporation for four years, the results showed that variable straw amounts had different effects on the soil fertility indices, where H treatment had the greatest effect. Compared with CK, the average soil available N, total N, available P, total P, and SOC levels under straw incorporation treatments were 27.5%, 10.8%, 16.6%, 5.2%, and 9.8% higher in 0–40 cm soil layers, especially in 0–20 cm soil layer. The straw incorporation treatments average increased the soil urease, phosphatase, and invertase activities levels by 19.6%, 39.4%, and 44.3% in 0–60 cm soil layers, according to the following order: H > M > L > CK. And higher yields coupled with higher nutrient contents were achieved with H, M and L compared with CK, where these treatments increased the crop yields by 22.5%, 22.8%, and 10.6%, and water use efficiency by 34.6%, 30.7%, and 15.7%, respectively. Our results suggest that straw incorporation (especially in rate of 13500 kg ha −1 ) is an effective practice for improving the soil fertility and increased crop yield in semiarid region of China.

Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China

Rainfall concentration for increasing corn production under semiarid climate

Soil aggregate and crop yield changes with different rates of straw incorporation in semiarid areas of northwest China

Plastic film mulching has been used widely to increase crop productivity in dryland farming. In this study, to identify the optimal mulching pattern and ensure the efficient utilization of soil water in the semi-arid areas of northwest China, we tested the following five treatments for 3 years (2013–2015): (1) full amount of plastic film with flat mulching (FL mulching) throughout the whole season (FLW), or (2) only during the growing season (FLG); (3) alternating ridges and furrows where only the ridges were mulched with plastic film (RF mulching) throughout the whole season (RFW), or (4) only during the growing season (RFG); (5) flat planting without mulching throughout the whole season (NM). The results showed that FLW was more beneficial for reducing soil water losses during the fallow season compared with RFW. FL mulching enhanced soil water consumption during the maize growing season, but promoted maize production compared with RF mulching due to the increased soil temperature. The rainfall was low during July–September in 2015, and the soil water storage at harvest under FLW and FLG were 9.13 mm higher and 8.01 mm lower than the stable soil water, respectively, thereby suggesting that FLW increased the soil water supply capacity in this drought year, and thus it was more sustainable in terms of soil water utilization compared with FLG. With FLW, the average yield increased by 838 kg ha−1, 1944 kg ha−1, 2363kg ha−1, and 5164 kg ha−1, compared with FLG, RFW, RFG, and NM, respectively, and the average net income increased by 244 USD ha−1, 520 USD ha−1, 643 USD ha−1, and 1166 USD ha−1. These results suggest that FLW was an effective method for substantially increasing economic benefits and maize yields in semi-arid areas.

Response of soil water, temperature, and maize (Zea may L.) production to different plastic film mulching patterns in semi-arid areas of northwest China

Xiaolong Ren

Papers

Effects on soil temperature, moisture, and maize yield of cultivation with ridge and furrow mulching in the rainfed area of the Loess Plateau, China

Effects of straw incorporation on the soil nutrient contents, enzyme activities, and crop yield in a semiarid region of China

Rainfall concentration for increasing corn production under semiarid climate

Soil aggregate and crop yield changes with different rates of straw incorporation in semiarid areas of northwest China

Response of soil water, temperature, and maize (Zea may L.) production to different plastic film mulching patterns in semi-arid areas of northwest China