Potassium nutrient response in the rice-wheat cropping system in different agro-ecozones of Nepal

Roshan Babu Ojha,Dinesh Panday,Shova Shrestha,Yajna Gajadhar Khadka,Vassilis G Aschonitis

doi:10.1371/journal.pone.0248837

Roshan Babu Ojha, Dinesh Panday + Show 3 more

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https://doi.org/10.1371/journal.pone.0248837

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Abstract

Most of the soils of Nepal had a higher potassium (K, expressed as K2O) level inherently. Later in 1976, the Government of Nepal has recommended K fertilizer rate at 30 kg K2O ha-1 in rice-wheat cropping systems. However, those crops began showing K deficiency symptoms in recent decades, which could be due to a large portion of soils with depleted K level or the insufficient input of K fertilizer for crop production. This study explored a limitation of K nutrient in the crops by establishing field trials from 2009-2014 at three agro-ecozones i.e., inner-Terai (2009-2010), high-Hills (2011-2012), and Terai (2012-2014) in Nepal. Seven rates of K fertilizer at 0, 15, 30, 45, 60, 75, and 90 kg K2O ha-1 were replicated four times in a randomized complete block design, where crop yields and yield-attributing parameters of rice-wheat cropping system were recorded. Results revealed that an increase in K rates from 45 to 75 kg K2O ha-1 under inner-Terai and Terai conditions and 45 to 60 kg ha-1 under high-Hills conditions produced significantly higher grain yields compared to the recommended K dose. Economically, the optimum rate of K fertilizer should not exceed 68 kg K2O ha-1 for rice in all agro-ecozones, or 73 kg K2O ha-1 for wheat in inner-Terai and 60 kg K2O ha-1 for wheat in high-Hills and Terai. Our findings suggest to increase potassium application in between 1.5 to 2.5 times of the current K fertilizer rate in rice-wheat cropping system of Nepal that need to be tested further in different locations and crop varieties.

Highlights

The rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system (RWCS) is the most important cropping system in the subtropical zone of South and Southeast Asia [1]
A significantly higher rice straw yield was obtained from 75 kg K2O ha-1 than the basal recommended K dose (BRKD) in the first and third years
Crop cultivation in the Terai region began after the clearing the forest in 1927 [47], and robust agricultural production was observed with the alluvial deposit, medium-textured, forest soils

Summary

Introduction

The rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system (RWCS) is the most important cropping system in the subtropical zone of South and Southeast Asia [1]. It covers an estimated 13.6 million ha in the Indo-Gangetic Plains (IGP) of India, Bangladesh, Nepal, and Pakistan [2] and provides a livelihood for hundreds of millions of people that contributes to regional food and nutritional security [3, 4]. Rice-wheat crop rotation is the most common rotation system in Nepal [5, 6]. The funder had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript

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