A spacing of 2.7 X 2.7 m is found to be optimum for the growth of arecanut crop.
Irrigation with 200 litres of water per palm once in 6 days through hose is recommended.
Recommended fertilizer dose for arecanut is 100g N, 40g P₂O₅and 140g K₂O / palm / year.
Studies in arecanut - cocoa cropping system revealed that it is possible for carbon sequestration to the tune of 7.16 t/ha to 14.83 t/ha annually.
Drip irrigation @ 20liters of water per palm per day results in 45% yield increase and 44% saving in water in arecanut.
With respect to optimization of fertigation dose and frequency, 50% and 75% of the standardized fertilizer dose was sufficient for pre-bearing and bearing arecanut palms, respectively through drip fertigation.
During bearing stage, the cost of cultivation was estimated at Rs. 60,242 and Rs. 26,377/- for conventional method and drip fertigation, respectively. Fertigation of 75% NPK at 10 days interval was highly profitable with highest net returns per rupee investment of 4.57 followed 75% NPK fertigation at 20 days interval (4.44).
In 12 year old arecanut (cv. Sreemangala), total biomass production was significantly greater in high yielders (43.6 kg palm-1) than in low yielders (30.8 kg palm-1). Trunk biomass accounted for 69% of the total biomass in high yielders and 74% in low yielders indicating less partitioning to other parts.
Total uptake of macronutrients by arecanut was in the order of N > K > Ca > P > Mg. The order of total uptake of micronutrients was Fe > Mn > Cu > B > Zn.
The yield levels of arecanut can be sustained at around 2600 kg ha-1 due to organic waste recycling. However, the response of arecanut to chemical fertilizers was more pronounced as the yield increase was 73-85% with NPK application compared to VC application alone (48-59%) and integrated treatments (46-63%) over control.
Vermicompost maintained higher SOC, soil test levels of P, Ca, and Mg than chemical fertilizers. Depletion of soil available K and accumulation of micronutrients was noticed in arecanut basins with vermicompost.
In arecanut based high density cropping systems having component crops like cocoa, pepper, banana and clove, comparatively similar yield levels and soil nutrient status was noticed with OMR and integrated use of chemical fertilizers and OMR.
The result emphasizes that the system can be self-sustainable over a long term period. Application of N and P through inorganic fertilizers could be reduced or skipped, while the system proved exhaustive with regard to the availability of K.
Intercropping of MAPs in arecanut increased the productivity per unit area by 272 to 1524 kg ha-1. This amounted to the total system productivity of arecanut + MAPs intercropping system to the tune of 2990 to 4144 kg ha-1 while the average sole arecanut yield was 2795 kg ha-1.
The net return per rupee investment was highest in Cymbopogon flexuosus (4.25) followed by Bacopa monnieri (3.64), Ocimum basilicum (3.46) and Artemisia pallens (3.12).
On the basis of yield, quality and economic feasibility, recycling of gliricidia prunings from standards and vermicompost application alone or in combination with husk mulching are better options for intercropped vanilla in arecanut.
Growing of vanilla on gliricidia standards did not affect the arecanut yield and the average kernel yield of arecanut during the experimental period was 3114 kg ha-1.
Optimum foliar concentrations for N, P, K, Ca and Mg were established as 2.70, 0.23, 1.12, 0.61 and 0.20%, respectively. Optimum micronutrient concentrations (mg kg-1) were estimated at 146 for Fe, 56.5 for Mn, 2.6 for Cu, 45.8 for Zn, 39.5 for B, 432 for Al and 63 for Na.
Optimum soil nutrient limits were higher for laterite soils in arecanut tract than generalized guidelines for interpretation of soil analysis data. At 0-30cm soil depth, optimum nutrient concentration for P, K, Ca, Mg, Fe, Mn, Cu, Zn and B was established as 15, 192, 925, 179, 37, 88, 26, 5.5 and 1.4 mg kg-1, respectively.
Nutritional disorders like crown choking, crown bending and oblique nodes in arecanut are due to deficiency of zinc and zinc deficiency in arecanut may be the result of complex interactions between DTPA extractable Zn and other nutrients in soil.
Softwood grafting is the most successful propagation technology
Canopy architecture by pruning and planned cutting of branches have been standardized for canopy management under intercropping and in sole crop
Cocoa is planted at a spacing of 2.7m x 5.4m in pits of 60 cm3 filled with compost in areca garden planted at a spacing of 2.7m x 2.7m with provision of shade.
When cocoa is to be raised as a mixed crop with coconut, cocoa can be planted at 2.7 m apart in single hedge system and 2.5m apart in paired rows in double hedge system between two rows of coconut palms.
The crop is to be irrigated once in a week during November-December, once in 6 days during January-March and once in 4-5 days during April-May with about 175 liters of water.
Systematic study for 10 years on drip irrigation and fertilizer requirement of cocoa mixed cropped in arecanut revealed that drip irrigation at E0 of unity (20 liters of water per day per tree) and a fertilizer dose of 100: 40: 140 g of N, P2O5 and K2O per tree per year would be optimum for cocoa.