Microbial Biomass Carbon, Activity of Soil Enzymes, Nutrient Availability, Root Growth, and Total Biomass Production in Wheat Cultivars under Variable Irrigation and Nutrient Management

Bipin Kumar,Sangeeta Paul,Ashraf M M Abdelbacki,Pravin Kumar Upadhyay,Shiva Dhar,Tarek K Zin El-Abedin,Venkatesh Paramesh,Anchal Dass,Shaimaa A M Abdelmohsen,Fatemah H Alkallas,Amit Kumar,Hosam O Elansary

doi:10.3390/agronomy11040669

Abstract

Intensive mono-cropping without a balanced supply of nutrients and declining water resources are degrading soil health, and as a consequence, agriculture production is becoming unsustainable and causing environmental degradation. The field experiment was conducted during Rabi season to assess the effect of an irrigation schedule, nutrient management, and wheat (Triticum aestivum L.) varieties on soil microbial biomass carbon (SMBC) and soil enzymes activities. Two nutrient levels, recommended rate of chemical fertilizer (RDF) and 50% RDF + 50% recommended dose of nitrogen (RDN) through farmyard manure (FYM) designated as Integrated Nutrient Sources (INS), and three irrigations levels, one irrigation at crown root initiation (CRI), two irrigations at CRI and flowering stages, and five irrigations at all main stages of the crop (CRI, tillering, jointing, flowering, and grain filling) were allocated to main-plots while four varieties of wheat, HD 2967, WR 544, HD 2987, and HD 2932, were allocated to sub-plots. The results revealed that SMBC and activities of dehydrogenase, alkaline phosphatase enzymes, and acid phosphatase were higher under restricted irrigation (irrigation at CRI stage) than other irrigation schedules. SMBC, dehydrogenase, acid phosphatase, and alkaline phosphatase activities were 73.0 µg g soil−1, 86.0 µg TPF g soil−1d−1, 39.6 µg PNP g soil−1 h1, and 81.8 µg PNP g−1 soil h−1, respectively, with the use of INS that was higher than RDF. Root weight and root volume followed a similar pattern. Applying single irrigation at CRI left behind the maximum available nitrogen (166.4 kg ha−1) in soil compared to other irrigation schedules and it was highest (149.31 kg ha−1) with the use of INS. Moreover, total organic carbon (TOC) was 0.44 and 0.43% higher with irrigation at CRI stages and the use of INS, respectively. The INS with single irrigation at the CRI stage is important to improve the root growth, SMBC dehydrogenase, alkaline phosphatase, and acid phosphatase enzyme activity in the wheat production system.

Highlights

Wheat constitutes the major staple food crop for people around the world
A significantly higher root volume was observed when wheat was irrigated only once at the crown root initiation (CRI) stage compared to irrigations given at all critical stages during both seasons (Table 1)
This study, which evaluated the effect of an irrigation schedule, nutrient management, and cultivar, provides first-time insights on the interaction effects of irrigation and nutrient management on the root characteristics and soil microbial activity

Summary

Introduction

Wheat constitutes the major staple food crop for people around the world. India is a privileged country in wheat production and is considered as the second-largest producer of wheat in the globe, registering a historic wheat production of 97.44 million tons (Mt) during 2016–2017 with an average productivity of 3.17 t ha−1. The rice-wheat is a major growing system in the countries of South-Asia, which grows about 13.5 million hectares (Mha), more than three-quarters of which are in India. The continuation of the rice-wheat growing system on the same land for several decades has resulted in a noticeable reduction of soil organic matter (SOM), soil fertility, and eventually reduced soil productivity. Cereal-based cropping systems are very exhaustive, especially concerning nutrients [1], and cause mining of soil nutrients

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Conclusion