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To ensure energy security and greenhouse gas emission, the world has decided to look for more sustainable and renewable energy sources. Biogas production from agricultural biomass is a fast growing market in the world. Suitable energy crops include maize, clover grass, alfalfa, sorghum, sudangrass, miscanthus and many others. Management considerations of energy crops such as harvesting time and nitrogen (N) application considerably influenced the biomass yield, quality of crop along with bio-methane production. Therefore, field study was conducted to determine the impact of harvesting times (HT) and nitrogen rates on the biomass yield of maize and production of bio-methane from it. The variable NR and HT, had a substantial influence on morphological, and compositional traits and bio-methane production. The N application at 200 kg ha-1 produced the taller plants, with maximum leaves, leaf area, biomass yield, protein contents, acid detergent fiber (ADF), neutral detergent fiber (NDF), and lignin contents. In addition to that higher nitrogen rate (200 kg ha-1) produced higher methane production however, it remained the same with 150 kg N ha-1. Harvesting at 65 DAS produced the maximum taller plants with maximum leaf area, biomass yield and had maximum ADF and NDF which negatively affected the specific methane yield. Moreover, harvesting at 65 DAS produced maximum methane yield (MP) due to higher biomass yield (BY). It is concluded that N application @ 150 kg ha-1 and harvesting at 65 DAS can be suitable for getting the higher bio-methane production under semi-arid conditions of Pakistan. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The water shortage in China, particularly in Northwest China, is very serious. There is, therefore, great potential for improving the water use efficiency (WUE) in agriculture, particularly in areas where the need for water is greatest. A two-season (2012 and 2013) study evaluated the effects of irrigation and fertilizer rate on tomato (Lycopersicum esculentum Mill., cv. “Jinpeng 10”) growth, yield, and WUE. The fertilizer treatment significantly influenced plant height and stem diameter at 23 and 20 days after transplanting in 2012 and 2013, respectively. As individual factors, irrigation and fertilizer significantly affected the leaf expansion rate, but irrigation × fertilizer had no statistically significant effect on the leaf growth rate at 23 days after transplanting in 2012. Dry biomass accumulation was significantly influenced by fertilizer in both years, but there was no significant difference in irrigation treatment in 2012. Our study showed that an increased irrigation level increased the fruit yield of tomatoes and decreased the WUE. The fruit yield and WUE increased with the increased fertilizer rate. WUE was more sensitive to irrigation than to fertilization. An irrigation amount of 151 to 208 mm and a fertilizer amount of 454 to 461 kg·ha−1 (nitrogen fertilizer, 213.5–217 kg·ha−1; phosphate fertilizer, 106.7–108 kg·ha−1; and potassium fertilizer, 133.4–135.6 kg·ha−1) were recommended for the drip fertigation of tomatoes in greenhouse. [ABSTRACT FROM AUTHOR]

In the semi-arid region of the Loess Plateau in China, the use of alternative field management practices is essential for sustainable agriculture. The purpose of this study was to investigate the effect of mulching and fertilization on the soil temperature, soil water content, soil nitrate-N content and grain yield of maize. The experiment was conducted over three consecutive years and used randomly assigned field plots with five replicates. The six treatments consisted of no fertilizer without plastic film (CK), no fertilizer with plastic film (ZM), basal fertilizer without plastic film (BN), basal fertilizer with plastic film (BM), basal and top dressing without plastic film (BTN) and basal and top dressing with plastic film (BTM). The soil temperature of the 10-cm mulching treatment was significantly higher than that of the no-mulching treatment, and the average soil temperature of the mulching treatment increased by 2.3 °C before July and nearly 1.2 °C after July. The soil water content in the mulching treatment was significantly higher than that in the no-mulching treatment at 0–60 cm, which was not significantly different from the 140–200 cm depth. The trend in the soil nitrate-N content distribution revealed symmetrical shapes along the center of the furrows, and the standard symmetrical distribution reduced gradually with an increase in soil depth under the plastic film mulching conditions. The soil nitrate-N content under basal fertilizer was 1.65 times higher than that without fertilizer at 0–10 cm at 36 days after sowing. The soil nitrate-N content in the topsoil was reduced from 48.67 to 30.77 mg/kg after 58 days. We found that plastic film mulching with basal fertilizer increased maize yield by 10.61%, 9.48%, and 15.36%, and top dressing increased the yield by 16.61%, 20.94%, and 12.24% over the three consecutive years. A treatment involving plastic film mulching, basal fertilizer and top dressing is recommended. Further studies are required to investigate the effect of mulching on increased soil temperature, soil water content and soil nitrate-N content, which simultaneously affect yield, and to determine the effects on the field microclimate. [ABSTRACT FROM AUTHOR]

Agriculture in the 21st century is facing multiple challenges, such as those related to soil fertility, climatic fluctuations, environmental degradation, urbanization, and the increase in food demand for the increasing world population. In the meanwhile, the scientific community is facing key challenges in increasing crop production from the existing land base. In this regard, traditional farming has witnessed enhanced per acre crop yields due to irregular and injudicious use of agrochemicals, including pesticides and synthetic fertilizers, but at a substantial environmental cost. Another major concern in modern agriculture is that crop pests are developing pesticide resistance. Therefore, the future of sustainable crop production requires the use of alternative strategies that can enhance crop yields in an environmentally sound manner. The application of rhizobacteria, specifically, plant growth-promoting rhizobacteria (PGPR), as an alternative to chemical pesticides has gained much attention from the scientific community. These rhizobacteria harbor a number of mechanisms through which they promote plant growth, control plant pests, and induce resistance to various abiotic stresses. This review presents a comprehensive overview of the mechanisms of rhizobacteria involved in plant growth promotion, biocontrol of pests, and bioremediation of contaminated soils. It also focuses on the effects of PGPR inoculation on plant growth survival under environmental stress. Furthermore, the pros and cons of rhizobacterial application along with future directions for the sustainable use of rhizobacteria in agriculture are discussed in depth. [ABSTRACT FROM AUTHOR]

• We evaluated the significance of root hydraulic conductance (Lp) and related parameter changes in water uptake and growth regulation of plants under different nitrogen (N) conditions. • The superiority of partial N deficit (D) in term of maize seedling growth was apparent and caused compensatory growth. • Higher plant dry mass in D might be attributable to the maintenance of a similar ΨL and improved shoot N content. • Compared with partial N resupply, partial N deficit was more advantageous to root water uptake and N accumulation at the same level of root surface area, thus resulted in higher dry mass of maize seedlings. Unexpectedly, at 21 day, the shoot dry mass in S could recover to the level of control. The regulation mechanisms in partial N resupply will be the focus of future studies. • When adopting the method of partial N application, it is necessary to consider the soil N condition before partial application. The influence mechanism of heterogeneous nutrient distribution on compensatory growth of maize seedlings is a key topic in the interaction between crops and soil environment. We evaluated the significance of root hydraulic conductance (L p) and related parameter changes in water uptake and growth regulation of plants under different nitrogen (N) conditions. Maize seedlings were grown in split-root containers containing N solutions. Three N treatments were applied: (1) full-strength N (control: C), in which both sub-root systems received 4.0 mM N (each sub-root: C44); (2) partial N deficit (D), in which each sub-root system received 2.0 mM N (D42) or full-strength N (D44); and (3) partial N resupply (S), in which both sub-root systems received 2.0 mM N for six days, followed by 2.0 mM N (S22) or full-strength N (S24). The shoot dry mass in D increased gradually with early development, and was greater than that in C and S within 15–21 day, suggesting that the superiority of partial N deficit (D) in term of maize seedling growth was apparent and caused compensatory growth. Moreover, the slope and intercept in D44 and D42 between Ψ L vs. L p and shoot N content vs. L p were obviously greater than that in C44, S24 and S22, indicating that higher plant dry mass in D might be attributable to the maintenance of a similar Ψ L and improved shoot N content. In addition, the slopes and intercepts in D44 and D42 between L p vs. root surface area and shoot N content vs. root surface area were higher than that in S24 and S22, suggesting that compared with partial N resupply, partial N deficit was more advantageous to root water uptake and N accumulation at the same level of root surface area, thus resulted in higher dry mass of maize seedlings. However, partial N resupply significantly increased root cortex thickness/diameter ratio and reduced root vessel diameter, which resulted in lower L p , Ψ L and shoot N content during 12–21 day. Unexpectedly, at 21 day, the shoot dry mass in S could recover to the level of control. The regulation mechanisms in partial N resupply will be the focus of future studies. Thus, when adopting the method of partial N application, it is necessary to consider the soil N condition before partial application. [ABSTRACT FROM AUTHOR]