The effect of leguminous cover crops on growth and yield of tomato

Abstract

Tomato (Lycopersicon esculentum L.) is one of the vegetable fruit crops commonly cultivated around the globe and used mostly as a flavour in cuisines. Cover cropping is a form of sustainable agriculture which helps to maintain soil fertility and reduces the need and the amount of inorganic fertilizer and thus helps the farmer to increase profitability. The objective of this study was to find the effect of the cover crops on growth and yield of tomato. In this experiment legume cover crops were grown in five treatment plots and these were Bare soil, inorganic fertilizer (NPK 15:15:15), Vigna unguiculata (Cowpea), Mucuna pruriens (Mucuna) and Canavalia ensiformis (Canavalia) in 3 blocks. The results showed that tomato plants grown on Canavalia ensiformis plots showed earlier flowering and fruiting than the other treatments. It also showed significantly higher yield than the other treatments (P= 0.006). The study shows that cover crops especially Canavalia ensiformis could be considered as part any farming system that wants to use sustainable farming to improve soil nutrients and reduce cost of farming. Keywords— Tomato, crop, conventional agricultural practices. I. BACKGROUND The use of cover cropping as a sustainable agriculture practice is not commonly practised in Ghana. Most farmers use conventional agricultural practices which include the use of inorganic fertilizer in quite high quantities, which could lead to ground water pollution. Vegetable fruits like garden eggs and tomato are cultivated by quite a high number of youth in the Eastern Region of Ghana. Vegetable production is the main source of income for some of these young farmers. This has helped quite a number of these farmers to be successful. Most of the vegetable products are sold in large towns and cities by middle men who buy at the farm gate. The use of well-managed sustainable agriculture practices could lead to high yield and environmental benefits. The use of cover crops could be for various reasons including recycling nutrients, reduced leaching of nutrients, weed control and improved soil and air quality (Hoorman, 2009). Legume cover crops have the ability to fix atmospheric nitrogen into usable forms in the soil by plants. Cover crops recycle nutrients and reduce the use of inorganic fertilizer. Among the commonly used legume cover crops are Canavalia spp., Crotalaria sp., cowpea, beans, groundnut, Mucuna sp. and Soybean. Legumes have been found to enhance soil fertility and increase crop yields (Abayomi et al., 2001). In a similar work, Kang (1992) found that legumes could have multiple uses including use as cover crops, live mulch or food crops. On the African continent, the use of Mucuna spp. as cover crop has received some attention. Ile et al., (1996) found that growing of Mucuna pruriens as a cover crop could reduce the need to apply synthetic nitrogen fertilizer. Ngome et al., (2011) found that growing maize and Mucuna pruriens together led to increase of maize yield. Although conventional agriculture has helped provided abundant food to feed people, it has led to reduced soil fertility and excessive use of pesticides (Smil, 1997, Trewavas, 2001) particularly on vegetables and fruits which have negative effects on human and animal health (National Research Council, 1989). Ways to achieve sustainable agriculture include organic farming, use of leguminous cover crops with reduced use of synthetic fertilizer and pesticides use (Fatima et al 2012). The use of sustainable agricultural system with sustainable inputs which enhances the environment in terms of air, soil and water has attracted research attention of late (Mattoo and Teasdale, 2010). Including cover crops in crop rotation led to decrease in nitrate leaching and increased ecosystem services (Alonso-Ayuso et al., 2018). Recent studies have shown that the use of cover crops led to improvement of C and N stocks in the soil for use by the succeeding crop (Buchi et al., 2018, Garcia-Gonzalez-Gonzalez et al., 2018, Landricini et al., 2019). International journal of Horticulture, Agriculture and Food science(IJHAF) Vol-3, Issue-5, Sept-Oct, 2019 https://dx.doi.org/10.22161/ijhaf.3.5.5 ISSN: 2456-8635 www.aipublications.com Page | 284 In this study, legume cover crops of Vigna unguiculata, Mucuna pruriens and Canavalia ensiformis were used as cover crops and compared with fertilizer application and bare ground. The objective of this study was to find the effect of the cover crops on growth and yield of tomato (Lycopersicon esculentum L. cultivar “Power”). II. MATERIALS AND METHODS The experiment started with the planting of cover crops in a Randomised Complete Block Design of 5 treatments in 3 blocks. The treatments were Bare Ground (Control) which acted as a check against Fertilizer N.P.K. 15:15:15 application, Vigna unguiculata (Cowpea), Mucuna pruriens (Mucuna), Cananalia ensiformis (Canavalia). The cover crop plots were planted with 25 seeds at a distance of 1m within and between rows. The cover crops were cut down when they reached the flowering stage and used as mulch and incorporated into the soil 2 weeks after transplanting. Seeds of tomato cultivar “Power” were nursed and transplanted onto the field when 3 weeks old. After one month each treatment was given 10 g of inorganic fertilizer (N.P.K. 15:15:15). Two weeks later, the fertilizer applied plots were given 20 g of the inorganic Fertilizer (N.P.K. 15:15:15). Parameters that were studied were shoot height, flowering time and yield. Shoot height was measured from the ground level to the terminal bud of an erect branch. Fifty percent flowering time was measured by counting when half (5) of the selected sampled plants had flowered. Yield was determined by the weight and number of fruits per plant on the sampled plants. Analysis of variance was performed using Genstat edition 14. III. RESULTS Plant height was highest in the Bare ground (Control) (73.27 cm) and lowest in the fertilizer (NPK 15:15:15) applied plots (66.37 cm) and the difference was not significant (P= 0.055, Fig.1). Fig. 1 Plant height and canopy spread of tomato plants on different treatment plots Canopy spread was widest in Canavalia-grown tomato plants (68.3 cm) and smallest in Mucuna treated plots (56.7 cm). The differences between them were not significant (p = 0.098). The number of fruits per tomato plant was highest in Canavalia treated plots and lowest in Mucuna plots. The treatments of the leguminous plots of tomato plants were not significantly different from that of the Control and the fertilizer applied plots (p = 0.228). 0 10 20 30 40 50 60 70 80 Canavalia Cowpea Mucuna Fertilizer Control Le n gt h ( cm ) Treatment Plant height