It is difficult to obtain high-protein contents from rice straw using direct fermentation due to its low nitrogen content. This study investigates the effects of ammonification–steam explosion pretreatment of rice straw on the protein content after solid-state fermentation (SSF). The pretreatment is carried out under multi-strain inoculation conditions. The samples of rice straw after ammonification (T_A), steam explosion (T_SE), and ammonification and steam explosion (T_A-SE) were compared to the control group (T_C). The results indicate that both ammonification and steam explosion could disintegrate rice straw’s lignocellulosic structure, releasing nutrients that can be used for microbial reproduction. In addition, amino compounds are formed along with depolymerization products, thus effectively promoting the true protein content. Post-fermentation, total crude protein contents of T_A, T_SE, and T_A-SE samples were 2.56, 1.83, and 4.37 times higher than that of Tc samples, respectively, and true protein contents were 2.52, 1.83, and 5.03 times higher. This study shows that the true protein content by combined ammonification and steam explosion pretreatment of rice straw during 96 h of solid-state fermentation was 46.7% of its total matter, rendering it a suitable alternative to high-protein animal feed.

Water scarcity in arid regions increases the need for technologies to improve water productivity. The integrated effects of plastic film mulching and water stress on grain maize under conventional and alternate furrow irrigation methods are still poorly understood in Sindh’s climate. Therefore, field trials were conducted at Malir farm, Sindh Agriculture University Tandojam, Pakistan, during the cropping season 2020–2021 to investigate whether mulching is practicable for grain maize production under the different furrow irrigation methods. The experiments involved two types of furrow irrigation, two water stress levels (sufficient and severe water stress), and plastic film mulching. Treatments were laid out in a randomized block design and three replications. The conventional and alternate furrow irrigation method was assigned to the main plot, while the water stress and plastic film mulching were in sub-plots. The results showed that different furrow irrigation methods significantly affected plant growth, grain yield parameters, and crop harvest index. Significant highest plant growth and grain yield of maize crop were observed with the conventional furrow irrigation (CFI) compared with the alternate furrow irrigation (AFI) method. However, grain yield and irrigation water productivity (IWP) were increased significantly by the plastic film mulching. The results revealed that sufficient water stress was more effective in sustaining grain yield and IWP than crop irrigating at several water stresses. The interaction effect of furrow irrigation and water stress, furrow irrigation, and plastic film mulching significantly impacted the IWP of grain maize. The IWP of the maize crop was significantly higher under the AFI than the CFI method if it was mulched with plastic film and irrigated at sufficient water stress level.

The most important factor impacting wheat production is water stress that occurs during the reproductive growth stage. Therefore, the plant responses and water productivity as affected by drought priming were investigated during Rabi seasons 2021 and 2022. The field trials were conducted in the research field of the Department of Irrigation and Drainage, Faculty of Agricultural Engineering, Sindh Agriculture University, Tandojam. The Hamal-BNS wheat variety was subjected to differing irrigation water regime levels (40%, 50% and 60% of soil water holding capacity, SWHC) after being subjected to drought priming, irrigation water recovery (water closure period) and drought priming. There were six treatments: (1) DPP-40 (drought priming plants at 40% of SWHC), (2) DPP-50, (3) DPP-60, (4) CTP-40 (controlled treated plants at 40% of SWHC), (5) CTP-50 and (6) CTP-60. During the experiment period, soil moisture content was significantly affected by the different treatments at various growth stages of wheat. The results indicated that winter wheat pre-exposed to drought priming attained a stress imprint that improved the subsequent deficit water levels which occurred during the later plant growth stage as demonstrated by the progress of test weight, grain yield, plant level water use efficiency and irrigation water use efficiency as well as relative yield compared to CTP-50 (control treatment). Under the irrigation water regime levels during the post-anthesis period, primed wheat plants sustained grain yield and higher relative yield than wheat plants without priming due to the better irrigation water regime for drought-primed wheat plants. Similarly, primed wheat plants consumed 18.3% less irrigation water as compared to non-primed plants, which significantly increased plant level WUE and irrigation WUE and decreased dry biomass and root development of drought-primed wheat plants. Therefore, to conserve fresh water for other field crops and increase water productivity in the Sindh province, it is recommended that drought priming is used during the early growth period of wheat plants as a successful irrigation method.

To examine the humification characteristics of crop residues, three types of crop residues—wheat, maize, and rice—were selected for experimentation. The latter two were subjected to steam explosion (SE) and nitrogen addition SE, respectively. Each of the three types of straw was inoculated in accordance with a specific microbial addition protocol. Furthermore, environmental controls, including the oxygen concentration and temperature type, were employed to enhance the variability of the samples. The results demonstrate statistically significant discrepancies in the concentrations of humic acid (HA) and fulvic acid (FA) between the three samples. Following a 96 h composting process, the highest concentrations of fulvic acid (FA) and humic acid (HA) in the samples were recorded at 10.4% and 15.8%, respectively. This result indicates the successful conversion of crop straw into a high-quality humic acid fertilizer product. Infrared spectroscopy data indicate that the breaking of carbon–carbon bonds and the ring opening, as well as the substitution of benzene rings, occurred during composting, and FA and HA substances were gradually formed. The results indicate that humus production is subject to raw materials, the pre-treatment of materials, the differentiation of strains, and methods of controlling environmental factors.

The combination of ammonia and steam explosion pretreatment has shown significant potential to enhance protein yield during the solid-state fermentation (SSF) of rice straw. However, the complex interactions between physicochemical changes and fermentation parameters necessitate precise optimization. This study employed a three-level Box–Behnken design (BBD) within the framework of Response Surface Methodology (RSM) to evaluate the effects of steam explosion pressure, pressure retention time, and ammonia concentration on protein yield. The SSF experiments were conducted in 5 L fermentation bottles using a co-culture of Aspergillus oryzae and Neurospora sitophila. The results demonstrated that the optimal conditions were a pressure of 1.44 MPa, a pressure retention time of 139.4 s, and an ammonia concentration of 8.3%. Under these optimized conditions, the protein yield reached 42.1% after 96 h of SSF, which was validated by a confirmatory experiment (42.8% ± 2.37%). The pretreated rice straw exhibited significantly improved lignocellulose degradation and structural porosity, providing a highly conducive substrate for microbial growth. These findings suggest that the optimized ammonia–steam explosion process is an effective and quantifiable strategy for converting agricultural waste into high-quality protein feed, contributing to sustainable bio-resource utilization.