**1. Introduction**

Rice and wheat are the forerunner staple food crops in imparting the energy for humans, directly through carbohydrate and protein as the main components of foods and indirectly through different provisional services. Out of the total protein consumption in India, 56.7% is from cereals [1], while 20% of per-capita energy for humans and 13% protein in the diet of nearly half of the world population were contributed by rice, and this share is much higher in developing countries [2]. The share of both crops to food grain production is 75.11%, while the share in total cereal production was 81.3% [3]. This indicates the role of rice and wheat in meeting the protein requirement of the Indian population. On another side, the contribution of rice and wheat to resource utilization among all crops

**Citation:** Shahane, A.A.; Shivay, Y.S.; Prasanna, R.; Kumar, D.; Bana, R.S. Effect of Crop Establishment Methods and Microbial Inoculations on Augmenting the Energy Efficiency and Nutritional Status of Rice and Wheat in Cropping System Mode. *Sustainability* **2022**, *14*, 5986. https:// doi.org/10.3390/su14105986

Academic Editors: Luis Hernández-Callejo, Sergio Nesmachnow and Sara Gallardo Saavedra

Received: 28 March 2022 Accepted: 26 April 2022 Published: 15 May 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

is the highest with 34.5% and 24.4% of the gross cropped area under rice and wheat, respectively [3]. At the same time, the share of rice in the total fertilizer consumption is 37% for nitrogen (6.98 million tonnes), 37% for phosphorus (2.76 million tonnes) and also 37% for potassium (0.977 million tonnes) in 2020–2021, respectively, and the same for wheat was nearly 24% for nitrogen (4.897 million tonnes) and 24% for phosphorus (2.155 million tonnes). Besides the above-mentioned natural resources, the monetary involvement is much higher in the cultivation of both crops with an average cost of cultivation for rice varying from Indian national rupee (INR) 1082.5 to 2732.6 for 100 kg grain yield, and the same for wheat varies from INR 1109.8 to 2233.9 for 100 kg grain yield, respectively [4]. The monetary criteria such as gross and net returns are used most commonly for calculating crop profitability, while for different artificial resources such as irrigation water, electricity, petroleum products, fertilizers, etc., which are purchased at a subsidized price, the present monetary evaluation is not complete. In this regard, the evaluation of all resources in a single unit, and with it the non-subsidized or original cost, is needed, and this can be carried out by the quantification of all inputs and outputs in terms of energetic and nutritional outcome. The need for accounting for energetics in crops and cropping systems along with monetary returns can be justified by increasing energy scarcity, increasing adoption of energy-efficient CEMs [5–7], the contribution of energy to greenhouse gas emissions and subsidies on fertilizers. As energy scarcity is aggravating and large variants for management practices and input additions are available, the study of these parameters for their energy efficiency will be an important scope and generate valuable scientific information. The requirement of energy per kg of crop produce and reduction in energy requirements for different field operations, and higher net energy production with the same level of resources, are useful criteria for judging efficiency in crop production. This high contribution of both crops to input consumption and meeting the energy and nutritional requirements of human beings creates scope to evaluate both crops in the cropping system mode for their energetic and nutritional outcomes.

Rice and wheat had significant variation in the crop establishment methods (CEMs) and cultivation methods and this can be explained by significant variations in hydrological regimes in rice ecosystems in India [8–11] and variation in tillage and land configuration in wheat [7,12]. The significance of energetics in a crop/cropping system has both economic and environmental bias. The largest contribution of the energy sector to global warming [13] with finite, limited and shrinking conventional (coal and petroleum-based) energy resources and increasing emphasis of policy makers on use of solar, wind and hydroelectric energy explain the environmental bias of energetics, while increasing the price per unit of energy leading to increasing prices of inputs, promotion of energy-efficient machines/equipment in crop production [14,15] and increasing wages of labour elucidate the economic bias of energy use. The energy equivalents given by different authors [16–18] indicate the highest energy equivalent per unit input was accounted by different nutrients. The energy equivalent for 1 kg nitrogen, phosphorus, potassium and Zn was 60.6 MJ, 11.1 MJ, 6.7 MJ and 20.2 MJ, respectively. The higher energy equivalent signifies the need for studying nutrient management variables for their role in energetics, while variation in CEMs and cultivation methods leading to variation in tillage requirements create scope for studying their energetics with varied levels of inputs. Along with the energy equivalent, the nutritional status of both crops needs to be studied considering their contribution to human nutrition and growing concerns of micronutrient deficiency [19,20] and other health-related risks [21,22]. The CEMs were studied for their energetics, while scientific information on the interactions of different CEMs and input additions (microbial inoculation, Zn fertilization and optimum and sub-optimum fertilization) on the energetic and nutritional status of RWCS is lacking, which was considered a research gap. Considering the increased number of crop establishment methods (CEMs) in RWCS with significant variations, the significant contribution of both rice and wheat to input consumption and human nutrition and the high energy equivalent of nutrients, the study was planned with two objectives: (i) to identify the energy-efficient CEMs in RWCS and the role of microbial

inoculations and Zn fertilization in enhancing the energetics of RWCS; and (ii) to know about the micronutrient uptake in rice and wheat as affected by applied treatments, thereby increasing the nutritional status of grains.
