Response of vanilla (Vanilla planifolia A.) intercropped in arecanut to irrigation and nutrition in humid tropics of India

A 5-year field trial to assess the impact of microsprinkler irrigation and nutrition on vanilla grown as intercrop in arecanut plantation was conducted on a laterite soil. Pooled analysis indicated that microsprinkler irrigation at 1.0Epan resulted in significantly higher green bean yield (842kgha⁻¹) than 0.75Epan (579kgha⁻¹). Organic manure application in the form of vermicompost (720kgha⁻¹) and FYM (768kgha⁻¹) and recommended NPK (718kgha⁻¹) produced green bean yield at par with recycling of gliricidia prunings (625kgha⁻¹). Irrigation at 1.0Epan proved superior by registering maximum benefit:cost (B:C) ratio of 2.25 compared to 1.62 at 0.75Epan. The highest B:C ratio was obtained with recommended NPK (2.27) followed by recycling of gliricidia prunings (2.10), vermicompost (1.87), vermicompost+arecanut husk mulching (1.80) and FYM (1.64). The soil pH increased by 0.4units in 2008 compared with the pre-experimental soil pH of 5.6 in 2004. Nutrition alone and in combination with irrigation had significant impact on soil pH. Organic manure application increased the soil pH (6.1-6.2) significantly over recommended NPK (5.6) at the end of experiment in 2008. Significant variation in soil organic carbon (SOC) was noticed due to different nutrition treatments. Application of vermicompost and FYM significantly increased the SOC content by 38-54% in 2008 over initial levels in 2004. Bray's P availability was influenced by nutrition and its interaction with irrigation. Application of FYM continuously for 4 years has resulted in significant increase in Bray's P content (41.3mgkg⁻¹) compared to other nutrition treatments (9.4-17.2mgkg⁻¹). Irrigation equivalent to 0.75Epan (223mgkg⁻¹) increased the K availability significantly over 1.0Epan (172mgkg⁻¹). The K availability was significantly higher in recommended NPK (416mgkg⁻¹) than in other organic treatments (98-223mgkg⁻¹) at 0-30cm soil depth. Overall, vanilla responded well to irrigation and nutrition in arecanut-based cropping system with a better economic output and improved soil fertility.