Legume-Based Mobile Green Manure Can Increase Soil Nitrogen Availability and Yield of Organic Greenhouse Tomatoes

Abstract

Information about the availability of soil mineral nitrogen (N) in organic greenhouse tomatoes after the application of mobile green manure (MGM), and its impact on plant nutrient status and yield is scarce. Considering this knowledge gap, the effects of legume biomass from faba beans that are cultivated outdoors (FAB), or from feed-grade alfalfa pellets at two different doses (AAL = 330 g m−2; AAH = 660 g m−2) that were applied as MGM on the nutrition and yield of an organic greenhouse crop of tomatoes were evaluated. All of the MGM treatments increased the mineral N concentrations in the soil throughout the cropping period, and the total N concentration in tomato leaves when compared to the untreated control. FAB and AAH treatments had a stronger impact than AAL in all of the measured parameters. In addition, AAL, AAH, and FAB treatments increased the yield compared to the control by 19%, 33%, and 36%, respectively. The application of MGM, either as faba bean fresh biomass or as alfalfa dry pellets, in organic greenhouse tomatoes significantly increased the plant available soil N, improved N nutrition, and enhanced the fruit yield. However, the N mineralization rates after the MGM application were excessive during the initial cropping stages, followed by a marked decrease thereafter. This may impose an N deficiency during the late cropping period.

The Effects of Differentiated Organic Fertilization on Tomato Production and Phenolic Content in Traditional and High-Yielding Varieties

“…In a recent study, Carricondo-Martínez et al (2022) [ 28 ] observed a reduced yield when using crop residues (C/N 15, yield 41.4 Tn/ha), composted goat manure (C/N 11, yield 41.0 Tn/ha), or composted vegetable waste (C/N 8.9, yield 43.2 Tn/ha) as compared with inorganic fertilizers used as a control (50 Tn/ha). While, in contrast, in other studies a higher production as compared with conventional mineral fertilization has been observed with the use of N-rich poultry manures or green manures [ 29 , 30 ]. Although the C/N ratio in our N-rich+C fertilizer was similar to that of the organic fertilizers used by Gatsios et al (2021) [ 29 ], we did not observe changes in productivity in any tested variety, perhaps because of the high fertility of our experimental field.…”

“…While, in contrast, in other studies a higher production as compared with conventional mineral fertilization has been observed with the use of N-rich poultry manures or green manures [ 29 , 30 ]. Although the C/N ratio in our N-rich+C fertilizer was similar to that of the organic fertilizers used by Gatsios et al (2021) [ 29 ], we did not observe changes in productivity in any tested variety, perhaps because of the high fertility of our experimental field. Similarly, Bénard et al (2009) [ 31 ] reported that low N supply rates had little impact on commercial tomato fruit yield.…”

The role of cover crops in improving soil fertility and plant nutritional status in temperate climates. A review

“…In another study, faba bean was found to be the most suitable CC for improving the nutrient composition of organic kale, whereas ryegrass CC determined a higher kale biomass production, thus highlighting the importance of species selection (Thavarajah et al 2019). Gatsios et al (2021), comparing the effects of two different mobile green manures in organic greenhouse tomatoes, indicated that faba bean green manure is more effective than alfalfa pellets in increasing the plant available soil N and tomato leaf N concentration. Faba bean green manure also proved to be economically advantageous, since it enhanced yield, fruit number per plant and mean fruit weight more than alfalfa pellets.…”

Fresh Pod Yield, Physical and Nutritional Quality Attributes of Common Bean as Influenced by Conventional or Organic Farming Practices

“…Seeking solutions with the aim to achieve healthier products through eco-friendly production systems, organic cultivation practices can be considered as a solution since inorganic N and synthetic agrochemicals are avoided. According to Gatsios et al [ 10 , 11 , 12 , 13 ], N supply in organic agriculture mainly relies on green and animal manures, composts, crop rotation with legumes, and utilisation of intercropping approaches. The introduction of the above-mentioned renewable N sources into agricultural production systems can also reduce contamination of water resources with nitrates [ 14 ] and increase the diversity of soil microbiota [ 15 ], thereby fostering soil nutrient availability, productivity, and health [ 16 ].…”