Understanding the effects of irrigation regime and soil texture on potassium-use efficiency (KUE) of rice (Oryza sativa. L) is essential for improving rice productivity. In this regard, experiments were conducted from July to October in 2016 and 2017 by using a randomized complete block design in a factorial arrangement with four replications. The rice plants were grown in three soils, with clay contents of 40%, 50%, and 60%, which were marked as S _(40%), S _(50%), and S _(60%), respectively. For each soil type, irrigation regimes, namely, R _{(F, S100%)}, R _{(F, S90%)}, and R _{(F, S70%)}, were established by setting the lower limit of irrigation to 100%, 90%, and 70% of saturated soil water content, respectively, and the upper limit of irrigation with 30 mm of flooding water above the soil surface for all irrigation regimes. Results showed that the responses of the roots and shoots and the potassium accumulation (KA) and KUE of rice were significantly affected by the water regime and soil texture. In the same irrigation regime, increasing the soil clay content improved the K utilization of rice. Under the same soil type, R _{(F, S100%)} was the optimal water management practice for growing rice. The R _{(F, S100%)} S _(60%) treatment presented the highest KUE, which was 56.4% in 2016 and 68.1% in 2017. The R _{(F, S70%)} S _(40%) treatment showed the lowest KUE, which was 13.8% in 2016 and 14.9% in 2017. These results enrich knowledge regarding the relationship among soil, water, and rice, and provide valuable insights on the effect of irrigation regime and soil texture on the KA and KUE of rice.

Despite the recent interest in biochar and digestate as soil amendments for improving soil quality and increasing crop production, there is inadequate knowledge of the effect of the combination of biochar and digestate, particularly under saline irrigation conditions. A pot experiment with Chinese melon was conducted in a greenhouse, biochar (5%) and digestate (500 mL/pot) were used with and without the recommended mineral NPK (Nitrogen, Phosphorus and Potassium) fertilizer dose (120-150-150 Kg ha⁻¹). The plants were irrigated with tap water (SL0) and 2 dS/m (SL1) NaCl solution. The growth, photosynthesis rate, water use efficiency (WUE) and yield of Chinese melon were affected positively when biochar was combined with digestate amendment, particularly under saline irrigation water with and without mineral NPK fertilizer. The maximum yield under normal water was obtained by digestate (SL0: 218.87 t ha⁻¹) and biochar amendment combined with digestate (SL1: 118.8 t ha⁻¹) under saline water. The maximum WUE values were noticed with the biochar and digestate combination under all water treatments (SL0: 32.2 t ha⁻¹ mm⁻¹ and SL1: 19.6 t ha⁻¹ mm⁻¹). It was concluded that digestate alone was more effective than the use of biochar, particularly with normal water. The combination of biochar with digestate had a significant effect on the Chinese melon growth, photosynthesis rate, water use efficiency and yield under saline irrigation, and it can be used as an alternative fertilizer for mineral NPK fertilizer.

This study aims to offer a comprehensive assessment of the impacts of policies and institutional arrangements on irrigation management performance. The case study, the Gezira Scheme, has witnessed a significant decrease in water management performance during recent decades. This situation led to several institutional changes in order to put the system on the right path. The main organizations involved in water management at the scheme are the Ministry of Irrigation & Water Resources (MOIWR), the Sudan Gezira Board (SGB), and the Water Users Associations (WUAs). Different combinations from these organizations were founded to manage the irrigation system. The evaluation of these organizations is based on the data of water supply and cultivated areas from 1970 to 2015. The measured data were compared with two methods: the empirical water order method (Indent) that considers the design criteria of the scheme, and the Crop Water Requirement (CWR) method. Results show that the MOIWR period was the most efficient era, with an average water surplus of 12% compared with the Indent value, while the most critical period (SGB & WUAs) occurred when the water supply increased by 80%. The other periods of the Irrigation Water Corporation (IWC), (SGB & MOIWR), and (WUAs & MOIWR) had witnessed an increase in water supply by 29%, 63%, and 67% respectively. Through these institutional changes, the percentage of excessive water supply jumped from 12% to 80%. Finally, the study provides general recommendations associated with institutional arrangements and policy adoption to improve irrigation system performance.

Nanospheres were prepared by different materials of nano-bamboo charcoal powder, zeolite powder, and aquaculture pond sediment in different ratios. It was then fermented with effective microorganisms (EM) active calcium liquid to synthesize the bioactive microbial nanospheres. These nanospheres were used to compare the purification effect of ammonium nitrogen (NH₄⁺-N), total nitrogen (TN), and total phosphorus (TP) pollutants in aquaculture wastewater. The indoor simulation experiment was also conducted to compare the different dosage methods (one-time dosing without aeration, multiple dosing without aeration, and multiple dosing with aeration) of microbial nanospheres on the removal of organic matter (OM) and effect of the biodegradability (G value) in aquaculture sediment. The results obtained indicated that the purification effect was most remarkable when the mass ratio of nano-bamboo charcoal powder: zeolite powder: pond sediment was 10%: 15%: 75%, in which the maximum removal rate of NH₄⁺-N, TN, and TP reached up to 84.86%, 52.15%, and 50.35%, respectively. Under the same microbial nanospheres amount, the effect of one-time addition on the removing of OM in sediment was not as effective as that of multiple dosing. After the 20th day, the removal rate of OM reached 25.99% in multiple dosing treatment and it was 35.58% higher than one-time dosing treatment. The OM content in sediment was reduced by 32.38% under the multiple dosing with aeration treatment. Multiple dosing of microbial nanospheres with aeration increased the G value of sediment about 337.0%. In situ experiment further indicated that the microbial nanospheres dosage with aeration had a good sediment bio-remediation effect, which is applicable to solve the problem of endogenous pollution in aquaculture ponds.

Digestate is increasingly utilized as a fertilizer, and earlier research was dedicated to plant growth and soil properties, with simple little information available regarding the effects of digestate on soil, plant, and microbial communities under saline irrigation. For this reason, a pot experiment with Chinese melon was conducted in a greenhouse, and digestate (1100 L ha⁻¹) and a full recommended dose of NPK fertilizer were used. The melons were irrigated with normal water 0.25 (SL0) and 2 dS/m (SL1) using sodium chloride (NaCl). Application of digestate increased the melon plant height and leaves number significantly (p < 0.05) compared to control and treatments that received full NPK dose, under both water treatments (SL0 and SL1). The maximum plant height (SL0: 161 cm and SL1: 85.5 cm) and leaves number (SL0: 156.33 and SL1: 69.67) were observed when digestate used with NPK fertilizer. Plant fruit length, fruit diameter, sugar content, and yield increased significantly by digestate addition. The melon fruit sugar content values were 12% (SL0) and 9.83% (SL1). Soil electrical conductivity values increased when digestate combined with NPK fertilizer (1.4 dS m⁻¹) particularly, under saline water, while the soil pH is not affected by digestate treatments. Digestate increased bacteria and decreased the number of fungi in the soil. Our results indicated that the usage of digestate could be more effective than NPK fertilizer on plant growth and soil properties. And there is a need to confirm these results in soils more realistic for agricultural field conditions and pay attention to use of digestate with saline irrigation water.