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Under sandy soil conditions, increasing the efficiency of potassium (K) fertilizers is considered to be a major limiting factor for improving the productivity and quality of fruit crops. In this context, utilizing nanotechnology has emerged as a novel technique to increase the efficiency of K applications. In our study, two field trials were conducted, in two consecutive seasons (2019/2020 and 2020/2021), to compare the effects of nano-chitosan loaded with K as a foliar treatment with those of conventional soil applications of K on plant growth, yield, and quality of strawberry plants grown in sandy soil. Strawberry plants were treated with 12 different treatments, which were replicated three times in a randomized complete block design in each growing season. Potassium sulfate (K2SO4, 48% K2O) was applied to the soil at a rate of 150.0 kg acre−1 (recommended rate, 100%). Meanwhile, the spraying of nano-chitosan loaded with K was applied at 1000 mg L−1 as a control. In addition, K2SO4 was applied either individually or in combination at the rate of 112.5 or 75.0 kg acre−1 with four nano-chitosan-K dosages (250, 500, 750, and 1000 mg L−1). After harvesting, soil samples were collected and prepared to determine K fractions. As well, plant samples were collected to determine the vegetative growth parameters and the foliage content of NPK and chlorophyll. Eventually, the yield traits and quality parameters were evaluated. A principal component analysis was conducted to determine the interrelationships of the treatments’ averages and their effects on yield components and quality traits. A combined analysis was performed for the two studied seasons and the values were the mean of six replications. The results indicated that the application of common K fertilizer (150.0 kg K2SO4 acre−1) resulted in the maximum increase in soluble and exchangeable K in the soil, which was comparable to those observed with 112.5 kg K2SO4 acre−1 + 1000 mg L−1 nano-chitosan-K and 112.5 K2SO4 acre−1 + 750 mg L−1 nano-chitosan-K. The total yield, marketable yield, and fruit firmness were all significantly increased by the latter two treatments compared to the control group. Furthermore, plots treated with 112.5 kg K2SO4 acre−1 + 1000 mg L−1 nano-chitosan-K significantly increased the total soluble solids, vitamin C levels, acidity, total sugar, and anthocyanin levels in strawberry fruits. In conclusion, under sandy soil conditions, the utilization of nanoparticles could be an indispensable tool for manipulating fertilization management when cultivating strawberries. The K status of the soil was improved by applying 75% of the recommended dose of mineral K in combination with 1000 or 750 mg L−1 of nano-chitosan-K, without compromising strawberry yield or quality.

The use of nitrogenous fertilizers in agriculture can cause uncontrolled gas emissions, such as N2O and CO2, leading to global warming and serious climate change. In this study, we evaluated the greenhouse gases emissions (GHGs) that are concomitant with applied different rates of N fertilization, such as 60%, 70%, 80%, 90%, 100%, 110%, and 120% of the recommended dose in green beans grown under three irrigation systems (surface, subsurface, and drip irrigation). The obtained results showed that GHGs were positively correlated with increasing the rate of N fertilization. Meanwhile, the subsurface irrigation system followed by drip irrigation achieved the highest significant (p ≤ 0.05) values regarding the growth and pod yield attributes. Furthermore, N supplements at 90% and/or 100% of the recommended dose under the subsurface irrigation system led to the highest concentration of chlorophyll, vitamin C, total protein, and activities of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POX). Proline and pod fibers were decreased in parallel with increasing the N rate, while water use efficiency (WUE) was improved with increasing the rate of N supplements up to 100% or 110% of the recommended dose.