The improvement of SOC sequestration mediated by soil structure in the greenhouse vegetable soil converted from paddy field

Objective of investigation: Land use conversion strongly alters soil structure and substantially affects soil organic carbon (SOC) sequestration. Changing from an anaerobic paddy field (PF) to a dry land easily causes SOC loss due to stimulation of C decomposition. However, no evidence of SOC loss from PF to intensive vegetable cultivation has been certainly presented. Experimental material: This study was conducted on the long-term cultivated open-field vegetable (OFV) and greenhouse vegetable (GHV) planting area converted from old PF in China. Undisturbed soil cores, natural structured soil, and disturbed soil from top soil layers were using for further analyses. Methods of investigation: To comprehensively investigate SOC and soil structure change in the land use conversion of PF to OFV and PF to GHV, we used 13C-CPMAS NMR spectroscopy to classify the SOC fractions. The soil macropores (> 50 μm) was valued by X-ray computed tomography, and soil aggregates distribution was determined by wet sieving method. Data collection: Data were obtained from the above-mentioned measurements and statistically analyzed in R. Results: The result showed that the SOC stock increased 1-fold from PF to GHV. SOC stability increased with recalcitrant C (aromatic-C and carbonyl-C) raised by 21 %–27 % in GHV bulk soil. Both macropores and macroaggregates (> 250 μm) increased in GHV, accompanied by an accumulation of recalcitrant C in large macroaggregates. Conclusions: we confirmed the expanded GHV cultivation sequestered more belowground SOC than PF, associated with the amplified physical protection by enhancing soil aggregation and by redistributing of soil macropores.

The potential importance of soil denitrification as a major N loss pathway in intensive greenhouse vegetable production systems

Background About 30 % of vegetables in China are produced in intensively managed greenhouses comprising flood irrigation and extreme rates of nitrogen fertilizers. Little is known about denitrification N losses. Methods Soil denitrification rates were measured by the acetylene inhibition technique applied to anaerobically incubated soil samples. Four different greenhouse management systems were differentiated: Conventional flood irrigation and over-fertilization (CIF, 800 kg N ha−1, 460 mm); CIF plus straw incorporation (CIF+S, 889 kg N ha−1, 460 mm); Drip fertigation with reduced fertilizer application rates (DIF, 314 kg N ha−1, 190 mm); DIF plus straw incorporation (DIF+S, 403 kg N ha−1, 190 mm). Soil denitrification was measured on nine sampling dates during the growing season (Feb 2019-May 2019) for the top-/ subsoil (0 – 20/ 20- 40 cm) and on three sampling dates for deep soils (40-60/ 80-100 cm). Data was used to constrain N-input-output balances of the different vegetable production systems. Results Rates of denitrification were at least one magnitude higher in topsoil than in sub- and deep soils. Total seasonal denitrification N losses for the 0 – 40 cm soil layer ranged from 76 (DIF) to 422 kg N ha−1 (CIF+S). Straw addition stimulated soil denitrification in top- and subsoil, but not in deep soil layers. Integrating our denitrification data (0-100 cm) with additional data on N leaching, N2O emissions, plant N uptake, and NH3 volatilization showed, that on average 50 % of added N fertilizers are lost due to denitrification. Conclusions Denitrification is likely the dominant environmental N loss pathway in greenhouse vegetable production systems. Reducing irrigation and fertilizer application rates while incorporating straw in soils allows the reduction of accumulated nitrate.

The promising variety of European radish Ophelia grown in protected and open ground conditions

Among the existing variety of vegetables, table root crops are very popular both in the Russian Federation and abroad: carrots, beets, radishes, turnips and parsnips. These crops are sources of natural vitamins; due to low prices for marketable products and seeds, they have been cultivated in Russia. Among all vegetables, radish ranks first by the content of potassium, magnesium and calcium salts; it also contains iron and phosphorus. When growing new varieties and hybrids of radish suitable for the mechanized harvesting, one should pay attention to the strength of leaves, the erectness of leaf rosettes, the uniformity of immersion in the soil and the easy pull-out of root crops. The collection of root crops Raphanus sativus L. VIR is annually replenished with numerous samples of the latest selection, primarily from China, Japan, and the Netherlands, as well as samples collected in Central Asia and the Caucasus. The main task of greenhouse vegetable growing is year-round or off-season production of high-quality vegetables (daikon, radish and turnip). As a result of the research, a new variety of European summer radish Ophelia was created for growing in protected and open ground conditions. It is an early ripening variety: it takes 33-38 days from full germination to the beginning of economic ripeness. Leaf rosettes are of medium size, light green. The vegetable has white elliptical roots. The Base is rounded. The pulp is white and opaque

Recommended cucumber hybrids for growing in greenhouses under conditions artificial lighting

For plants, light is a determining factor in growth and development. The use of artificial lighting in greenhouses has a huge impact on the yield, cost and timing of the receipt of vegetable products. The development of light culture in the country allows greenhouse complexes to use their greenhouses year-round, significantly increase plant productivity, receive most of the harvest in the winter months of the year and sell it at a higher price. The use of artificial light made it possible to increase the yield of the cucumber crop to 200 kg from 1 m2 or more. From the economic point of view, the cucumber culture is most effective in greenhouses. Russia is a cucumber country, more than half of the protected ground area is occupied by this crop. And photoculture in greenhouses began with the cultivation of a cucumber crop. Today we say with confidence that artificial lighting in greenhouses is more efficient than natural lighting. So to get one kilogram of vegetables using artificial lighting, it is necessary to spend 4.5-5.0 thousand J/cm2, and in the case of using natural light – 5.0-6.5 thousand J/cm2. This can be explained by the fact that in the conditions of using artificial lighting in cultivation facilities, we strive to create the most comfortable growing conditions for plants. An increase in the yield of cucumber crops under artificial lighting occurs mainly due to an increase in the lighting power per unit area of greenhouses to 220 W/m2and more. However, this is not the only way to increase yields. One of the most important criteria for increasing yields and improving the quality of fruits is the choice of the grown hybrid. Cucumber hybrids for cultivation under light culture conditions will be discussed in this work.The methods used in agronomic science were used. The information base of the research was made up of reference materials from specialized publications on the subject under study (catalogs of breeding companies); materials received from participants in the greenhouse vegetable market (breeding companies, greenhouse plants); own research, articles and reviews in specialized journals.Correctly selected cucumber hybrids provide a significant increase in yields in greenhouses, an improvement in fruit quality and a balanced cultivation technology in specific conditions. An assortment of recommended cucumber hybrids for cultivation under photoculture conditions is presented, an analysis of their advantages and disadvantages is made, and the main requirements for hybrids for these conditions are formulated.