Possible use of soluble organic manure for coco-peat grown cucumber (Cucumis sativus)

Hydroponics culture is becoming widely popular due to its yield and quality advantages as well as fast degrading arable lands in the world. However, its inevitable use of inorganic fertilizers has hindered its products' entry into high-value eco-friendly markets. Therefore an immerging trend is developing in the world toward the possible use of alternative plant nutrient sources in small-scale hydroponics vegetable production systems. This research effort was made to examine the effectiveness of selected organic manures and agricultural by-products in drip fertigated coco-peat (hydroponics) culture. Cucumber was selected as the test crop and the research was conducted under tropical greenhouse conditions in Sri Lanka during the rainy season. Organic manures were selected based on the experience gained in two similar experiments conducted in 2015-2016. Cattle manure, poultry manure, vermiwash, fish pond water and ash were used in appropriate combinations and ratios (based on their N, P and K compositions), as alternative sources of plant nutrients. In this way it was aimed to replace the inorganic hydroponics fertilizer, Alberts^® at the rate of 50-75% in coco-peat culture of cucumber (Cucumis sativus L). Standard agronomic practices and IPM options for plant protection were practiced. Plant growth, crop yield and fruit quality of cucumber in the control (100% Alberts^®) and organic manure based hydroponics treatments were not significantly different. The composition of N, P, K in leaves confirmed this result. Hence it was revealed that two combinations; 1) cattle manure with vermiwash and ash, and 2) poultry manure with fish pond water and ash could successfully replace the inorganic fertilizer up to 75% in coco-peat culture. The mixture (1) showed significant beneficial effects on plant growth, compared to mixture (2).