K. Susan John

Long-Term Effect of Lime, Mycorrhiza, and Inorganic and Organic Sources on Soil Fertility, Yield, and Proximate Composition of Sweet Potato in Alfisols of Eastern India

A field experiment was conducted for five kharif seasons (2006–2011) in an Alfisol to study the effect of integrated use of lime, mycorrhiza, and inorganic and organics on soil fertility, yield, and proximate composition of sweet potato. Application of graded doses of nitrogen, phosphorus, and potassium (NPK) significantly increased the mean tuber yield of sweet potato by 44, 106, and 130 percent over control. Green manuring along with ½ NPK showed greater yield response over that of ½ NPK. The greatest mean tuber yield was recorded due to integrated application of lime, farmyard manure (FYM), NPK, and MgSO4 (13.69 t ha−1) over the other treatments. Inoculation of mycorrhiza combined with lime, FYM, and NPK showed a significant yield response of 10 percent over FYM + NPK. Conjunctive use of lime, inorganics, and organics not only produces sustainable crop yields but also improve soil fertility, nutrient-use efficiency, and apparent nutrient recovery in comparison to NPK and organic manures.

Effect of Lime, Inorganic, and Organic Sources on Soil Fertility, Yield, Quality, and Nutrient Uptake of Sweet Potato in Alfisols

Field experiments were conducted in Alfisols to study the effect of integrated use of lime, inorganic, and organic manures on soil health and sweet potato performance. Integrated use of nitrogen, phosphorus, and potassium and farmyard manure recorded a significantly higher tuber yield (18.7 Mg ha−1) followed by lime + farmyard manure + neem cake + green manure (17.7 Mg ha−1). Incorporation of organics and 100% nitrogen, phosphorus, and potassium showed a yield response of 23%, 2%, and 10% in respect of farmyard manure, neem cake, and green manure over nitrogen, phosphorus, and potassium. A yield response of 12%, 10%, and 13% was observed due to incorporation of lime along with ½ nitrogen, phosphorus, and potassium and organics (farmyard manure, neem cake, and green manure) over that of unlimed plots. Conjunctive use of organic manures along with balanced fertilizers and lime not only produces higher crop yields but also enhanced the efficiency of added nutrients and sustains the soil fertility.

Optimizing the nutritional status of a typic kandiustult of Kerala, India, using sorption study

Abstract Nutrient sorption studies were carried out as a part of a mega project on “Yield maximization in cassava (Manihot esculenta Crantz) through systematic approach in fertilizer use” to find out the sorption characteristics of major, secondary, and micronutrients [i.e., phosphorus (P), potassium (K), sulfur (S), copper (Cu), zinc (Zn), manganese (Mn), and boron (B)] in a typic kandiustult of Kerala, India. The sorption curve fitted by using this study along with the results of preliminary soil analysis and critical level of these nutrients were used to optimize the nutritional status of this soil. Sorption study revealed that P, K, S, and B were limiting and others were sufficient for this soil. The quantities of the limiting nutrients required to optimize the soil nutritional status were estimated from the sorption curve as P, K, S, and B at 136 µg mL−1, 0.338 meq 100 mL−1, 20 µg mL−1, and 6.025 µg mL−1, respectively.

Yield Maximization in Cassava through a Systematic Approach in Fertilizer Use

Abstract Maximum yield research (MYR) and maximum economic yield systems (MEY) are important under the present situation of increased demographic changes, which have reduced the per capita availability of both land and food. Among root and tuber crops, cassava is found in a variety of production systems and performs well under various levels of management from low‐input to high‐input systems. A systematic approach in fertilizer use involves the determination and elimination of soil nutrient constraints for balanced supply of all potentially deficient essential nutrients for sustainable high yield. In the systematic approach of determining optimal fertilizer for cassava (Manihot esculenta Crantz) in a Typic Kandiustult soil of Kerala, India, studies on critical levels of nutrients, original nutritional status of the soil, its sorption capacity, and greenhouse/screenhouse nutrient survey were carried out. The critical levels of phosphorus (P) and potassium (K) were determined as 8.23 and 43.5 µg g−1, respectively. The preliminary analysis of the soil of the experimental site revealed the overall fertility status as very poor. The sorption studies conducted for P, K, copper (Cu), zinc (Zn), manganese (Mn), sulfur (S), and boron (B) indicated P, K, S, and B were limiting in this particular soil. The quantities of these nutrients needed to optimize the soil nutrient status were determined from the preliminary soil analysis, critical levels of nutrients, and sorption curves and found to be 136 µg mL−1 P, 0.338 meq 100 mL−1 K, 20 µg mL−1 S, and 6.025 µg mL−1 B, respectively. From the greenhouse nutrient survey, N, P, K, and calcium (Ca) were seen as limiting nutrients for this soil; therefore the optimum treatment for cassava was fixed as N‐P‐K at 100:300:300 kg ha−1, respectively. Field experiments were conducted for two seasons with different levels of the optimum treatment using a short duration (6–7 months) cassava variety, Sree Vijaya. The optimum treatment gave a yield of 43.41 t ha−1, whereas the yield under the existing practice recommendations was 20–25 t ha−1. Economic analysis showed this optimum treatment as the best in terms of highest gross return (Rs 1,31,125/‐), net return (Rs 83,150/‐), added return (Rs 70, 178/‐), added profit (Rs 56,142/‐), and benefit cost ratio (BCR) (2.73).