Excessive long-term application of chemical fertilizers may negatively impact on environmental ecosystems and reduce the soil quality which consequently may reduce crop productivity. Overpopulation in the Egypt has led to an increase in the demand for food, which focused the attention to raise the crops production [1, 2]. This led to an increase in the use of chemical fertilizers, especially in the cultivation of vegetable crops, where large amounts of chemical fertilizers are used in order to obtain the highest productivity [3]. The rates of chemical fertilizers used in the cultivation of vegetable crops are increasing compared to other crops because of intensive cultivation, which leads to exacerbate and increase the harmful effects on health and the environment, especially the residual effect of nitrate [4]. Although chemical fertilizers provide nutrients that are immediately available to plants to rapidly improve plant growth and crop yield, these fertilizers cannot replace the soil organic matter (SOM) that may be lost due to intensive cultivation [5, 6]. Maintaining appropriate levels of SOM is important as it ensures efficient nutrients, which contributes to sustainable management of sandy soil [7]. Instead, vermicompost (VC) and compost (CT) application can increase the content of SOM, which improves soil fertility and crop production.
For organic farming, VC and CT have been used as important alternatives to chemical fertilizers because chemical fertilizers are prohibited in organic farming [8, 9]. VC is a kind of natural eco-manure, which is the product of organic matter degradation through the interaction between earthworms and microorganisms (10–12]. As a result, VC is regarded a nutrient-dense biofertilizer with a diversified microbial community (13–14]. VC contains nutrients that are readily taken up by the plants, such as, available-P, K, Ca and Mg. VC is an excellent soil amendment or conditioner because of high porosity, aeration, drainage, water-holding capacity and microbial activity [15]. Vermicomposting and composting are two distinct processes, and it is crucial not to confuse the two [16]. The vermicomposting process produces a high diversity and number of microorganisms because the temperature during VC production is suitable for worms [17]. Vermicompost was used as an organic fertilizer for several crops under greenhouses and fields conditions (Pierre-Louis et al. 2021). Extraordinary decrease in the C: N ratio of VC was testified than that was in the CT [18, 19].
Zucchini (Cucurbita pepo L.) is one of the most important vegetable crops grown in Egypt for the local market. Zucchini plants belong to the cucurbit family (Cucurbitaceae), which are very diverse and popular for human consumption throughout the world [20]. However, zucchini fruit contain many nutrients, bioactive compounds (antioxidants, flavonoids, vitamins) and have a high amount of dietary fiber, which is very low in calories [21]. However, intensive zucchini cultivation practices in Egypt need to use large amounts of chemical fertilizers, partly resulting in over-fertilization, soil degradation, and a decrease in SOM content. Therefore, it is necessary to provide alternatives to improve the sustainability of zucchini production.
Soil degradation and its expansion are considered the greatest problem in Egypt, directly affecting food security and crop production [22, 23]. Soil nutrients are necessary for crop growth and development and are critical factors for soil fertility along with adequate soil moisture, which is considered a key factor for crop growth and yield [24, 25]. Therefore, manipulating nutrient release is an advanced and effective way to maintain sustainable zucchini production [26, 27]. Farmers assume that the extensive use of CF leads to better yields of various crops without considering the hazardous effects on the environment. However, the continuous use of CF has negative impacts on the soil quality [28, 29].
To ensure a healthy diet and reduce the environmental risks of chemical fertilizers, and in line with sustainable development programs that call for a return to nature, the current study was conducted to evaluate the effects of replacing CF with VC and CT on soil fertility, growth, yield, and fruit quality of zucchini cultivation under field conditions. We hypothesized that VC and CT treatments would help produce zucchini fruit free from residual effect of CF and improve sandy soil properties under semi-arid conditions in Egypt.