Zero-waste technology of watermelon seed cultivation

Abstract

Purpose. To investigate the agrophysical and agrochemical properties of soil, the course of physiological processes in watermelon plants under the influence of individual elements and cultivation technology as a whole, to determine their impact on improving seed quality. To develop a zero-waste technology for watermelon seed cultivation under non-irrigated conditions in the southern Steppe of Ukraine. Methods. Field, laboratory, measurement and calculation, comparative, mathematical-statistical analysis. Results. It was established that the highest reserves of productive moisture in the meter soil layer during watermelon sowing are formed with deep primary soil cultivation – from 110.3 mm to 114.6 mm and shallow cultivation + ridge formation – from 110.2 mm to 112.2 mm. The lowest reserves of productive moisture accumulate during shallow primary soil cultivation – from 90.2 mm to 94.2 mm. Applying the recommended dose of mineral fertilizers under watermelon with deep primary soil cultivation increases the nitrate nitrogen content from 2.8–3.6 to 11.4–12.4 mg/kg of absolutely dry soil. Significant increase in nitrogen content from applying the recommended fertilizer dose under watermelon, compared to the «no fertilizers» variant, is observed for shallow cultivation and shallow cultivation + ridge formation, respectively, from 2.1–3.1 to 11.4–13.6 mg and from 1.8–3.5 to 11.6–13.0 mg per kg of absolutely dry soil. The least weedy watermelon crops are observed after deep primary soil cultivation, where the average total weed count, depending on mineral nutrition levels, ranges from 8.8 to 16.7 pcs./m², while weed infestation with shallow primary soil cultivation ranges from 24.8 to 39.1 pcs./m². Ridge formation to a depth of 40–45 cm in combination with shallow primary soil cultivation provides a seed yield increase of 43.6 kg/ha compared to just shallow primary soil cultivation. The highest seed yield was obtained by applying shallow primary soil cultivation together with autumn ridge formation, local application of N20P30K20 mineral fertilizers, and planting with a feeding area of 1.5 m² – 114.0 kg/ha, which is 17.0 kg/ha more than in the control (deep primary soil cultivation, application of N60P90K60, feeding area of 2.0 m²). Seeds obtained from deep primary soil cultivation or shallow cultivation + ridge formation and fertilizer application have the best seeding qualities in terms of weight of 1000 seeds and protein content. Economically, the most advantageous cultivation of watermelon for seeds is under shallow primary soil cultivation + ridge formation, applying 1/3 of the recommended dose of N20P30K20 mineral fertilizers, and planting with a feeding area of 1.5 m², where the net profit is 9590 UAH/ha, production profitability is 234% with seed cost of 35.9 UAH/kg. A zero-waste technology for watermelon seed cultivation under non-irrigated conditions in the south of Ukraine has been developed, consisting of shallow primary soil cultivation + ridge formation to a depth of 40–45 cm, local application of N20P30K20 mineral fertilizers, planting with a plant feeding area of 1.5 m², minimal manual labor costs in the technological process of plant care, mechanized fruit harvesting and seed separation, and the possibility of by-product utilization. Conclusions. It was determined that on southern chernozems with low-humus loamy soils under non-irrigated conditions in the southern Steppe of Ukraine, to ensure consistently high watermelon seed yields and create conditions for soil fertility preservation, moisture accumulation, and rational utilization, it is necessary to implement the zero-waste technology of watermelon seed cultivation. This technology combines shallow primary soil cultivation + ridge formation to a depth of 40–45 cm, local application of N20P30K20 mineral fertilizers, planting with a plant feeding area of 1.5 m², minimal manual labor costs in the technological process of plant care, mechanized fruit harvesting and seed separation, and the possibility of by-product utilization.