Long-term impact of fertilizers and manures on sesame productivity under rainfed cultivation

Introduction

Soil is a key natural resource and soil health is the integrated effect of management on most soil properties that determine crop productivity and sustainability (Sharma et al., 2005) [1] . Continuous cultivation with high yielding varieties and high analysis fertilizers is unavoidable in Indian Agriculture, which accelerated the mining of nutrients from soil. Since large amount of nutrient has to be applied to soil in chemical form which may have impact on soil properties and soil productivity in long term. Conducting a long-term experiment at fixed site with continuous cropping will help to monitor the changes in soil quality and crop yields sustainability and also guide strategies for fertilizer management and minimize environmental degradation. The maintenance of the soil health is essential not only for maximizing agricultural production but also vital for sustaining the higher productivity levels in crops (Velu and Subramaniam, 2012) [2] . A judicious combination of organic amendments and inorganic fertilizers is widely recognized strategy of integrated nutrient management (INM) to sustain crop productivity and improve soil fertility (Manna et al., 2005) [3] . The earliest long-term experiments called Permanent Manurial Experiments were started at Rothamsted Experimental Station, Harpenden, Herts, England between 1843 and 1856 by J.B. Lawes and J.H. Gilbert and are known as 'Rothamsted Classical Experiments'. These experiments were neither replicated nor randomized. These experiments have been continued for more than 150 years and have yielded most valuable information for adoption of an efficient approach for managing the crops and cropping system (Elayarajan et al., 2013) [4] . Based on the Rothamsted model, the Permanent Manurial Experiment (PME) of Tamil Nadu Agricultural University (TNAU) started during the year 1909 remains successful among a few of permanent manurial experiments, which are being continued for more than 100 years in India and abroad. The principal aim of this experiment was to evaluate the long-term effect of inorganic and organic manuring on crop productivity and soil health.

Materials and Methods

Experimental details

The present study, part of an ongoing nationally renowned, well recognized, monumental and old Permanent Manurial Experiment (PME) of Oilseeds Research Station, Tindivanam, TNAU, India. This trial is being carried out in Randomized Block Design with 12 treatments replicated four times. The groundnut crop is being taken up during Kharif and cold weather gingelly is taken up after the harvest of Kharif groundnut as Rabi cold weather gingelly. Kharif and rabi sowing with respective crops were carried out continuously. The soil is fine loamy typic Ustropept Tindivanam series. The treatment details are T1-FYM @ 12.5 t ha -1 T2-50% optimum NPK T3-100% optimum NPK; T4-100% NPK + FYM @ 6.25 t ha -1 ;T5-100% N alone; T6-100% N & P alone; T7-100% N & K alone; T8-100% K + FYM @ 12.5 t ha -1 ; T9-100% NPK + FYM @ 12.5 t ha -1 ;T10-100% NPK + FYM @ 12.5 t ha -1 + herbicides; T11-100% N + Enriched FYM with optimum P & K; T12-Absolute control; The nutrient potential of FYM was characterized before the application in every year. The N, P and K content varied between 0.39 to 0.40, 0.14 to 0.16 and 0.7 to 0.8 respectively.

Inputs added

Organic Manures FYM: 6.25 and 12.5 tonnes ha -1 Enriched FYM: 750 kg ha -1

Inorganic Fertilizer

Groundnut: Recommended dose of Fertilizers 10:10:45 (NPK kg ha -1 ) Gingelly: Recommended dose of Fertilizers 23:13: 13 (NPK kg ha -1 ) Herbicide: Pendimethalin weedicide was applied @2 lit/ha

Plant and soil sampling and analysis

At harvest, seed, stover yield of Groundnut and grain, stover yield of sesame were recorded and expressed in kg ha-1. Average yields of both crops were made of the yield data for each fertilizer treatment over 10 years. Based on this, sustainable yield index (SYI) of the individual crop was calculated by the following Eq. (1) (Singh et al. 1990) [5] .

Experimental results

From the five years of research on Kharif groundnut and cold weather gingelly cropping system under pure rainfed condition without any supplemental irrigation revealed that, inputs applied as pure organic such as FYM or inorganic nutrient through fertilizers not produced maximum yield. But soil physical quality such as bulk density and porespace can be improved through the application of organic manures as compared to inorganic fertilizers. The soil microbial count also increased in the organic manures applied treatments. The data are given in Annexure tables. Integrated nutrient management through organic, inorganic and herbicide will give better yield along with no deterioration of soil quality. From the 5 years period of permanent manurial experiment revelled that 100% [email protected] -1 + Pendimethalin weedicide was applied @2 lit/ha. statistically superior than the other treatments with organic or inorganic source alone. So the general interpretation is that the treatments which received FYM alone or inorganic nutrients alone could not record statistically maximum yield, while the treatments that received 100% inorganic nutrients and 100% FYM topped in giving maximum yield under Kharif groundnut and cold weather gingelly.

Conclusion

The integrated application of organic (FYM @12.5 t ha -1 and inorganic (100%) NPK+ herbicide application has been found to be the most suitable nutrient application under pure rainfed condition for sustainable soil health and yield of groundnut and gingelly. This technology will showcases in all the capacity building and exposure visit programmes to farmers and extension functionaries. The trial plot will be used for field visit of the famers and extension functionaries.

References

1. Elayarajan M, Sathya S, Arulmozhiselvan K. Effect of Continuous Fertilization on Yield and Nutrient Uptake by Maize and Sunflower in Red Calcareous Soil (Typic haplustalf) under Permanent Manurial Experiment. Madras Agric J. 2013;100(4-6):424-428.
2. Subbaiah BV, Asija GL. A rapid procedure for estimation of available nitrogen in soils. Curr Sci. 1956;25(8):259-260.
3. Stanford S, English L. Use of flame photometer in rapid soil test K and Ca. Agron J. 1949;41:446-447.
4. Walkley A, Black JA. An estimation of digestion method for determining soil organic matter and a proposed modification of chromic acid titration method. Soil Sci. 1934;37:29-38.