Grass (Paspalum notatum) clippings, with and without cattle wastewater, supported production of organic cherry tomatoes in pots

ABSTRACT Plant residues are often composted prior to use as organic amendments or fertilisers, but in this study a new approach, referred here to as greenponics, was evaluated, using undecomposed plant biomass as the growing substrate and fertiliser. Cherry tomatoes ( Solanum lycopersicum) cv. Perinha Água Branca, were grown in 8 L pots filled with 600 g of air-dried bahia-grass clippings (Paspalum notatum). Soil (750 g) was placed in the centre of the pot, into which the tomato seedling was transplanted, and on the top (1250 g) to retain the moisture in the grass. At 63 days after transplanting, an additional 300 g of grass clippings were applied to each pot. Three treatments were applied as microbial inoculants to support the mineralisation of nutrients from the grass; a control (tap water) and two types of dairy cattle wastewater, applied raw or after treatment in a constructed wetland system. For each treatment, nine doses of 150 mL of water/wastewater were applied manually during the experiment. The control and the raw wastewater treatment produced 937 and 913 g marketable fruit plant−1, respectively, yields similar to those reported in the literature for organic cultivation of the same cultivar. Application of the treated wastewater resulted in lower yields (811 g plant−1), indicating that the grass clippings did not necessarily require the microbial inoculant to release nutrients for the growth of the tomatoes. Greenponics with grass clippings as the only source of fertiliser could be recommended as a potential alternative for growing cherry tomatoes in pots.