Growth and yield responses of four leafy vegetables to organic fertilizer

A.H. Lim and P. Vimala

Abstract

Four leafy vegetables, namely, leaf mustard (Brassica juncea), kangkung (Ipomoea reptans), chinese spinach (Amaranthus sp.) and lettuce (Latuca sativa), were grown on a clay loam soil with increasing rates of poultry manure (0, 10, 20, 30 and 40 t/ha), with and without inorganic fertilizer. There were altogether ten treatments. The rate of inorganic fertilizer (N:P2O5:K2O:MgO = 12:12:17:2) applied was 1 t/ha. The mean plant height of leaf mustard increased from 19.6 cm at 24 days after sowing (DAS) to 39.2 cm at 32 DAS and the mean leaf number was 6.7 and 9.7 respectively. The mean yield was 5.5 kg/plot and 337.7 g/plant. For kangkung, the mean plant height was 33.1 cm at 22 DAS and 46.7 cm at 29 DAS, and the mean yield was 6.2 kg/plot and 156.2 g/plant. Height of chinese spinach at 22 DAS and 29 DAS was 36.8 cm and 66.7 cm respectively with a mean yield of 7.2 kg/plot and 188.2 g/plant. Lettuce gave a mean height of 20.8 cm for both 48 DAS and 54 DAS. Its mean leaf number was 11.0 at 38 DAS, 31.2 at 48 DAS and 32.1 at 54 DAS, with a mean yield of 6.6 kg/plot and 164.0 g/plant. For most of the vegetables, application of 10 t/ha poultry manure (PM) gave lower yields than inorganic fertilizer alone. Generally, 20 t/ha PM gave comparable yields to inorganic fertilizer alone. The optimum yields obtained for leaf mustard, kangkung, chinese spinash and lettuce were 19.9, 24.1, 29.6 and 24.0 t/ha respectively. The yields resulted from optimum application of organic fertilizer at 28.75 t/ha (leaf mustard), 29.79 t/ha (kangkung), 35.98 t/ha (chinese spinash) and 29.92 t/ha (lettuce).

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