This study was carried out on the rotation of cowpea-rye + cowpea in successive crops for green manure-sorghum grains, with the objective of increasing the fertility of sandy soils by incorporating green cowpea manure into the soil in combination with chemical fertilization with NPK. In this sense, after harvesting the rye plant, the cowpea was sown, which was then incorporated into the soil during the formation of the beans in the pod. Before incorporating the cowpea biomass into the soil, the initial fertility status of the soil was assessed, and in the spring, the soil was sown with sorghum grain in two fertilization variants (N80P80K80 and N150P80K80). The soil chemical analyses carried out at the end of the vegetation cycle of the sorghum plant showed that by incorporating 52.4 t/ha green cowpea biomass (9.24 t/ha dry biomass), the quality properties of the soil were significantly improved, with annual increases of 0.17–0.29 g/kg in total nitrogen, 9.5–13.33 mg/kg in extractable phosphorus, 11.33–24 mg/kg in exchangeable potassium, and 0.08–0.12 g/kg in organic carbon, also depending on the sorghum fertilization system. It has also been shown to reduce the acidity of the soil pH and improve the water holding capacity of the soil.

As a result of the low organic matter content of the sandy soils in Romania, for the success of most crops, large amounts of chemical fertilizers are needed, which can often lead to the pollution of groundwater with nitrates, given the poor hydrophysical properties in terms of retaining chemical elements by these soils. In this sense, the study carried out in the period 2020-2023 within the rotation cowpea-rye+cowpea successive crop-sorghum for grains, aimed to promote the system of sustainable agriculture, by incorporating into the soil, in the form of green manure, the cowpea sown in succession after the rye. The soil quality analyses, carried out the following year after harvesting sorghum for grains, showed that by incorporating 52.4 t/ha of cowpea biomass into the soil between October 15-20, the quality characteristics of the sandy soil improved significantly. Thus, compared to the initial state of soil fertility, there were annual increases of 0.017-0.029%, in total nitrogen, by 9.5-13.3 ppm, in extractable phosphorus, by 11.333-24 ppm, in exchangeable potassium and by 0.008-0.012%, to organic carbon, also depending on the sorghum fertilization system. Also, the incorporation of green cowpea manure into the soil contributed to reducing the acidity of the soil pH and improving the water holding capacity of the soil profile.

The aim of this study was to monitor the development of the maize plant depending on the preceding plant (rye; alfalfa for forage), with the objective of promoting crop rotation with alfalfa jumping plots within the agricultural system practiced on sandy soils. The results obtained showed that alfalfa incorporated into the soil after five years had a positive effect on soil fertility and implicitly on the behavior and productivity of maize. Thus, the content of organic matter, left in the soil after incorporating alfalfa, was 4.3 times higher than that recorded in the soil with the preceding plant rye. The beneficial role of the alfalfa precursor plant was highlighted on the stress behavior of the maize plant, which best regulated its resistance mechanism to stress conditions by binding at the cellular level a percentage of water bound to 3.03%, higher by 0.43% compared to maize sown after rye. Also, the maize sown after alfalfa showed better character stability, the coefficients of variability having lower values compared to the maize grown after rye, and at harvest the grain production was 27.9% higher, compared to the sown after rye, the difference in production being statistically significant.

The climate changes from the recent decades, and the decline of stone fruit plantations (peaches and apricot) in the sandy soil area, have led the fruit researchers from Research Development Station for Plant Culture on Sands Dăbuleni to look for another line of fruit species, namely exotic fruit species. One of these species is the Chinese date, which in the seven years of study in the experimental lot at Dăbuleni, fruiting from the second year after planting and managed to become known as a fruit produced on the sands of Dăbuleni, or named ”the Dăbuleni jujube”. Although the research station only owns 1.5 ha demonstration plot, it has managed to sell jujube fruits to consumers across the country through online commerce. The fruits were sold in various stages of ripening, panda and completely brown fruits. Thus, the purpose of this paper is to present the nutritional values of Chinese date fruits at different maturation stages for six genotypes. At the end of the study, the vitamin C content in the fruit showed the highest values recorded in the Xuan Cheng Jiang genotype (305.41 mg/fresh fruit) in the fully brown stage, and in the „panda stage” the Lang genotype recorded the highest vitamin C content (283.51 mg/100g fresh fruit).

Citrullus lanatus belongs to the Cucurbitaceae family and is mainly cultivated in warm areas, representing a basic crop for them. Watermelon fruits are intended for fresh consumption, but can also be used for various preparations such as syrup, jam, or pickles. The study of the seven watermelon hybrids was carried out at the Research - Development Station for Plant Culture on the Dăbuleni Sands, in the period 2023 - 2024, with the aim of evaluating their behavior by determining the qualitative and morphological characteristics of the fruits. Among the analyzed hybrids, 5 are with red core (ʹKaristan F1ʹ, ʹKandemir F1ʹ, ʹMirsini F1ʹ, ʹLusitana F1ʹ and ʹPata Neagră F1ʹ) and two with yellow core (ʹPeace F1ʹ and ʹRoyal King F1ʹ). Following the determinations, the ʹKandemir F1ʹ hybrid stood out for the size of the fruits (12.55 kg - 11.22 kg) and the diameter of the fruits (25.68 cm - 26.66 cm). From a biochemical point of view, the ʹMirsini F1ʹ hybrid with the percentage of soluble dry matter (12%) and the ʹPeace F1ʹ hybrid with 14.38% of total dry matter stood out. The obtained results provide information regarding the degree of adaptation of the different watermelon hybrids to the pedo-climatic conditions in the area of sandy soils in the south of Oltenia.