Global crop yields are limited by water and nutrient availability. Soil mulching (with plastic or straw) reduces evaporation, modifies soil temperature and thereby affects crop yields. Reported effects of mulching are sometimes contradictory, likely due to differences in climatic conditions, soil characteristics, crop species, and also water and nitrogen (N) input levels. Here we report on a meta-analysis of the effects of mulching on wheat and maize, using 1310 yield observations from 74 studies conducted in 19 countries. Our results indicate that mulching significantly increased yields, WUE (yield per unit water) and NUE (yield per unit N) by up to 60%, compared with no-mulching. Effects were larger for maize than wheat, and larger for plastic mulching than straw mulching. Interestingly, plastic mulching performed better at relatively low temperature while straw mulching showed the opposite trend. Effects of mulching also tended to decrease with increasing water input. Mulching effects were not related to soil organic matter content. In conclusion, soil mulching can significantly increase maize and wheat yields, WUE and NUE, and thereby may contribute to closing the yield gap between attainable and actual yields, especially in dryland and low nutrient input agriculture. The management of soil mulching requires site-specific knowledge.

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Soil mulching significantly enhances yields and water and nitrogen use efficiencies of maize and wheat: a meta-analysis.

Addition of organic material, such as crop straw mulch in most soils is considered a strategy for sustainable agricultural production. We conducted a two-year experiment in 2015 and 2016 to determine changes in soil biochemical properties and maize yield in response to treatment with wheat-straw mulch. The treatments consisted of the addition of different levels of wheat-straw mulch (S1: 0, S2: 2500, S3: 5000 kg ha−1). Soil samples from four depths (0.1, 0.2, 0.3, and 0.4 m) were collected and analyzed. Soil enzymes, such as invertase, phosphatase, urease, and catalase, were significantly higher in the S3 treatment than in the S1 treatment. Values were greater for the samples collected at 0.1 m soil depth than those collected from deeper soil layers. Regarding soil properties, soil organic carbon (SOC), available nitrogen (AN), available phosphorus (AP), total nitrogen (TN), total phosphorus (TP), and soil water content (SWC) were significantly higher in S3 at 0–0.1 m soil depth than in other treatments. Compared with the (S1), an average increase in SOC, AN, AP, TN, TP, and SWC in 0–0.4 m soil depth with full straw mulch (S3), were 32.4, 31.9, 32.0, 11.8, 16.7, and 18.5%, higher, respectively. On average, urease, phosphatase, invertase, and catalase increased by 15.1, 11.0, 88.4, and 24.0%, respectively in the S3 treatment compared with that in the S1 treatment at 0–0.1 m depth, and decreased with increasing soil depth. The S3 treatment had increased grain yield (7%), biomass yield (28%), and water use efficiency (8%), compared with the S1 treatment. Overall, our results suggested that the S3 straw mulch treatment (5000 kg ha−1) could be used to sustain maize productivity and promote a better relationship between soil enzymes and soil properties in the semi-arid conditions of the Guanzhong area.

Changes in soil enzymes, soil properties, and maize crop productivity under wheat straw mulching in Guanzhong, China

The demand for food is expected to significantly increase with continued population growth over the next 50 years, indicating that agricultural efficiency should be simultaneously stabilized and enhanced. Here, we discuss the effects of mulching and nitrogen (N) fertilizer on the soil environment and crop yield to inform food security. The use of mulch in agriculture provides many benefits to the soil by reducing evaporation, improving temperatures, adjusting the microbial biomass, maintaining the soil organic carbon balance, increasing nutrient cycling, promoting soil enzyme activity, enhancing soil aggregate stability and suppressing weed infestation. Nitrogen fertilization can markedly improve soil fertility and crop yield. However, nitrogen use efficiency (NUE) and the environment may be negatively affected by the improper application of N fertilizers. The improvement of NUE has been an important focus in field management for the more sustainable use of valuable N fertilizers. A better understanding of the interaction between N and mulch may improve NUE and crop yields. Inorganic mulches more efficiently alter the soil environment to enhance the NUE and crop yield, while organic mulching materials are more environmentally friendly and inexpensive. The selection of appropriate mulching materials should be combined with effective N management strategies, crop species, crop management practices and climatic conditions. In the future, precise nitrogen fertilizer management on farms and the development of relatively high-NUE and high-yielding crops will be highly feasible.

The Effects of Mulch and Nitrogen Fertilizer on the Soil Environment of Crop Plants

Impacts of plastic film mulching on crop yields, soil water, nitrate, and organic carbon in Northwestern China: A meta-analysis.

Effects of plastic film combined with straw mulch on grain yield and water use efficiency of winter wheat in Loess Plateau

Understanding mulching influences on nitrogen (N) activities in soil is important for developing N management strategies in dryland. A 3 year field experiment was conducted in the Loess Plateau of China to investigate the effects of mulching, N fertilizer application rate and plant density on winter wheat yield, N uptake by wheat and residual soil nitrate in a winter wheat-fallow system. The split plot design included four mulching methods (CK, no mulch; SM, straw mulch; FM, plastic film mulch; CM, combined mulch with plastic film and straw) as main plot treatments. Three N fertilizer rates (N0, 0 kg N ha−1; N120, 120 kg N ha−1; N240, 240 kg N ha−1) were sub-plot treatments and two wheat sowing densities (LD, low density, seeding rate = 180 kg ha−1; HD, high density, seeding rate = 225 kg ha−1) were sub-subplot treatments. The results showed that wheat yield, N uptake, and N use efficiency (NUE) were higher for FM and CM compared to CK. However, soil nitrate-N contents in the 0–200 cm soil profile were also higher for FM and CM compared to CK after the 3 year experiment. Wheat grain yields were higher for SM compared to CK only when high levels of nitrogen or high planting density were applied. Mulching did not have a significant effect on wheat yield, nitrogen uptake and NUE when soil water content at planting was much high. Wheat yield, N uptake, and residual nitrate in 0–200 cm were significantly higher for N240 compared to N120 and N0. Wheat yield and N uptake were also significantly higher for HD compared to LD. When 0 or 120 kg N ha−1 was applied, HD had more residual nitrate than LD while the reverse was true when 240 kg N ha−1 was applied. After 3 years, residual nitrate-N in 0–200 cm soil averaged 170 kg ha−1, which was equivalent to ~40% of the total N uptake by wheat in the three growing seasons.

Yun Li

Papers

Effects of mulch, N fertilizer, and plant density on wheat yield, wheat nitrogen uptake, and residual soil nitrate in a dryland area of China