MSc

The research programme entitled “Productivity, carbon and nutrient stocks in mulberry (Morus indica L.) and subabul (Leucaena leucocephala Lam.) based high density fodder production system in coconut”, was conducted at Instructional farm, College of Horticulture, Vellanikkara during 2017-18, to evaluate the influence of tree density and harvest interval on forage yield, carbon and nutrient stocks of three- years- old mulberry and subabul fodder banks in coconut garden. The study also examined the variation in coconut productivity and soil fertility changes associated with fodder bank integration in coconut plantations. The treatments included intercropping of fodder tree species like mulberry and subabul-1 at three levels of tree densities (49,382; 37,037 and 27, 777 plants ha-1 ) and three levels of harvest intervals (8, 12 and 16 weeks) in all possible combinations with randomized block design replicated thrice. The study indicated that annual fresh fodder yield from fodder tree banks per hectare of coconut garden in the third year of intercropping was significantly higher in mulberry (33.93 Mg ha-1 yr ) than that of subabul (20.14 Mg ha-1 yr ). Forage yields of tree banks increased from 18.97 to 35.04 Mg ha yr from lower to higher density classes, and were also found to be higher (33.98 Mg ha-1 yr ) for medium harvest interval of 12 weeks than longer or shorter intervals. Comparing the cumulative effects of stand management practices, forage yields of mulberry and subabul stands showed drastic variation which ranged from 16.40 to 63.38 and 9.33 to 30.96 Mg ha-1 yr-1respectively under various management levels, there by indicating the critical role of proper management for productivity enhancement from tree fodder banks. Maximum yield was obtained from the highest density stand (49,382 plants ha-1 ) and at medium harvest interval of 12 weeks in both the tree species. In general, fodder tree intercropping and various management regimes showed no significant influence on coconut productivity. However, a slight decrease in nut yield was observed under very high fodder tree density (49,382 plants ha-1 ), especially with that of mulberry, there by pointing out the need for crop specificnutrient and moisture supplementation to prevent competition and yield loss in coconut under high density intercropping. Intercropping of fodder trees and various management practices resulted in significant enhancement in total biomass production and carbon storage potential of coconut plantations (82.70-108.48 Mg ha-1 ) than that of coconut monoculture system (75.35 Mg ha-1 ). The intercropped fodder trees have fixed additional carbon to a maximum of 33 Mg ha-1 in the plant biomass and in soil up to 40 cm depth, thereby making considerable contribution for reducing atmospheric carbon dioxide levels. Significant difference was observed in nutrient uptake by the two fodder tree species, tree density and harvest schedule. N, P and K uptake was found to be significantly higher for mulberry (70.77, 4.80 and 38.22 kg ha-1 ) than that of subabul (51.62, 2.97 and 24.45 kg ha-1 ). N, P and K uptake enhanced by 81, 113 and 96 per cent from lower to higher densities. The nutrient uptake was higher in the medium interval of 12 weeks when compared to shorter or longer intervals. In general, intercropping practices in coconut have overall improved the fertility status of soil compared to coconut monoculture. However, proper nutrient supplementation should be ensured while adopting very high tree densities to avoid any possible competition with coconut palms. Fodder tree species and tree density had significant effect on soil properties like pH and water holding capacity (WHC) in mulberry and subabul plots intercropped in coconut plantation. Soil pH was observed higher in subabul (4.84) than mulberry (4.58). Water holding capacity (WHC) was observed higher in mulberry plots (53.96 %) than that of subabul (50.84%). Comparing the economics of tree fodder integration in coconut garden, significantly higher B: C ratio was obtained from mulberry (2.94) than subabul (2.54). B: C ratio showed an increasing trend (2.26 to 3.05) from lower to higher density classes. The highest B: C ratio (3.07) was obtained from 12 weeks harvest interval.Hence, the present field study clearly demonstrates the possibility of integrating mulberry and subabul fodder banks in coconut gardens of Kerala to enhance quality forage production, so as to minimize farmer’s expenses on feed cost. Adoption of ideal stand management practices viz., tree density of 49,382 plants ha-1 and 12 weeks harvest interval, can generate higher forage yields from limited land area. Moreover, the intercropped fodder trees have fixed additional carbon to a maximum of 33 Mg ha-1 , thereby making considerable contribution for reducing atmospheric CO2 levels to minimize global warming. Thus, establishment and proper management of mulberry and subabul fodder banks in coconut garden is a low cost technology to enhance quality forage production in humid tropics, and a promising strategy for climate change mitigation via carbon sequestration.