TY - BOOK AU - Susan John K AU - Venugopal V K (Guide) TI - Yield Maximization in Cassava (Manihot esculenta Crantz) though Hunter`s Systematic Aproach in Fertilizer use U1 - 631.4 PY - 2003/// CY - Vellayani PB - Department of Soil Science and Agricultural Chemistry, College of Agriculture N2 - Among the tropical tuber crops, cassava is a faithful friend to more than 500 million people world wide who depend on its starchy root for food, feed and cash. The highest biological efficiency coupled with drought tolerance and ecological adaptation to soils of marginal fertility makes this crop important in the food economy. It is used as an animal feed and raw material for industry particularly starch production other than human consumption. Cassava though will grow on relatively infertile soils which are unsuitable for other crops, it responds well to fertilization. With selected HYV and proper fertilization yields of25 to30 t ha! are common and this can exceed 50 t ha:' with appropriate soil test based balanced fertilization and manuring. With a view to realize the maximum yield potential in cassava by optimizing the nutritional status of the soil, a series of experiments were undertaken under the present study entitled "Yield maximization in cassava (Manihot esculenta Crantz) through Hunter's 'systematic approach' in fertilizer use". This involved preliminary soil analysis, sorption study and green house nutrient survey to demarcate the nutrient constraints and also to optimize the soil nutrient status. The critical level of P and K for the particular soil series was also done since the basic concept of this approach is based on the critical level of nutrients in soil. Pot culture studies were undertaken to find out the critical level of P and K of Vellayani soil series Typic Kandiustult using maize as indicator crop. The level was fixed as 8.20 and 8.23 J.l g KI P and 43.5 and 45.5 J.l g g' K by the scatter diagram model and discontinuous regression model respectively. The preliminary analy~is of the soil of the experimental site indicated the overall fertility status of the soil as "poor" with acidic soil reaction, low availaibility ofN and K, medium in P and organic carbon, very low in Ca and Mg but satisfactory in micronutrient levels. 2 Sorption study was performed for P,K,Cu,Zn,Mn,S and B to find out if any ofthe applied plant nutrients fixed or complexed abnormally with the soil. From the sorption curve fitted Cu, Zn and Mn were seen as nonlimiting where as P,K,S and B as limiting based on the results of critical levels and preliminary soil analysis. The optimum quantities oflimiting nutrients were calculated from these basic experiments as 136 J.1. g ml:' P, 0.338 meq 100 ml:' K, 20 J.1. g rn1~1 S and 6.025 J.1. g ml' B. The green house or screen house nutrient survey was conducted to arrive at the optimum treatment and. also to check whether the optimum fixed is the real optimum treatment. For formulating the optimum treatment, N was applied at the rate of 50 J.1. g ml:' , P, K and S and B were added at the above concentration. Ca and Mg were applied @ 0.270g CaC03 and 0.092 g MgC03 to maintain Mg/K and CalMg ratio in the specified range as 1.6to 14 and 1.2 to 6.2. Fe was not limiting, but Mo @2 J.1. g ml' was also included since the pH is 4.8. Hence there were altogether 14 treatments with optimium (1) comprising of nutrients viz., N,P,K,Ca,Mg,S,B and Mo, these elements one by one were excluded from the optimum (8) and the non limiting elements Fe,Mn,Cu and Zn were included one by one to the optimum (4) and an absolute control (1). This experiment conducted with Sorghum (CO-5)as indicator crop and the relative yield calculated from the biomass yield recorded at 45th day of planting revealed N ,P,K and Ca only as limiting for the particular soil. These nutrients were selected' for the field experiment with cassava variety Sree Vijaya, a short duration line released from Central Tuber Crops Research Institute, Thiruvananthapurarn. From the earlier three basic studies the optimum levels ofN ,P and K were fixed as 100:300:300 kg ha-'. Four levels of these nutrients viz; zero, sub optimal, optimal and super optimal levels were taken. The treatments include one of the four levels of 3 one nutrient along with optimal levels of the other two nutrients. Moreover, Ca along with optimum also was included. These were compared with POP. These treatments along with FYM @ 12.5 t ha:' also constitute another set of treatments and there was an absolute control also. In addition, four more treatments were included to study the effect of substitution of cornrnonsalt for muriate of potash, altogether forming 29 treatments replicated twice in RBD. The effect of these treatments on growth characters, yield and yield components, total plant drymatter production and nutrient uptake revealed the significant effect of higher levels as optimal and super optimal levels in effecting higher production and hence on the interrelated parameters. Optimum treatment along with FYM produced a tuber yield of 40.75 t ha" and 43.41 t ha' respectively during the first and second year. Moreover, the super optimal level of one of the nutrients along with optimal levels of the other two nutrients were equally effective in achieving such a higher production. It was obvious that increasing levels ofN and diminishing rates ofK substantially increased cyanogen content and slightly reduced the starch per cent of cassava tubers. The chemical properties viz., organic carbon, available N,P and K were substantially affected" by higher levels of fertilizers. The nutrient use efficiency computed indicated the highest agronomic efficiency of Nil' and K associated with optimum + FYM. A reduction in N,P,K use efficiency at increasing levels of the respective nutrients where as it was modified at increasing rates of app1ciation of other nutrients. Studies on nutrient balance sheet showed a deficit balance after two years of experimentation and application of higher levels of one nutrient led to reduction in the loss of other nutrient. 4 The optimwn quantity ofN,P and K calculated based on quadratic polynomial response surface function was III to 115 kg ha" and 95 to 116 kg ha" N, 228 to 408 kg ha' and 299 to 345 kg ha-I P and 317 to 445 kg ha'! and 289 to 392 kg ha" K without and with FYM respectively. Economic analysis of the use of higher levels offertilizers indicated optimwn + FYM as the most appropriate in terms of highest gross return (Rs. 1,31,225 ha'), net return (Rs. 83,150 ha"), added return (Rs. 70,178 ha"), added profit (Rs. 56,142 ha") and BeR (2.73). The effect of substitution of common salt for muriate of potash on tuber yield indicated partial and full substitution both alone and along with FYM are similar in effecting tuber production but yielded substantially lower than no substitution. However, partial substitution along with FYM was equally well to no substitution without FYM. Hence the present investigation to realize the maximum yield potential in cassava through 'systematic approach' in fertilizer use by taking into account the nutritional constraints of the soil, manipulating these limiting factors and optimising the nutrient status could achieve a potential yield of 43.41 tha' over the normal average yield of 20-25 tha' under prevailing package of practices recommendations. So it is worth mentioning that the fertilizer management strategy developed by this approach CaR be recommended after field level confirmation for large scale cultivation of cassava in the acid laterite soils of Keralal as well as for industrial use by starch factories particularly in the Salem, Erode, Namakkal and Dharmapuri districts ofTamilnadu, Samalkot and Peddapuram areas East Godavari district of AndhraPradesh. Hence it is contemplated that with little more technological back ups and market support these crops may asswne the role of a commercial crop and gain importance as a raw material for animal feed and starch based industry in the coming decades. UR - http://krishikosh.egranth.ac.in/handle/1/5810015114 ER -