Assessment of yield and input-output energy and economic indicators in different tillage and fertilizer systems of corn (Zea mays L.)

Although industrial agriculture achievements are undeniable, its negative consequences such as biodiversity loss, pollination and human health are remarkable. Currently, yields of the world’s four most important crops would need to increase by around 60-110% by 2050. Agro ecological practices contribute to agro ecosystem redesign, efficiency increase and substitution practices based on various processes such as bio fertilizer, reduced tillage, reducing the use of nonrenewable energy. Corn is an important crop in the world and Khuzestan with a huge amount of inputs and energy uses during its production. There for, the assessment of agro ecological practices is essential for sustainability in corn production.

In order to study yield, energy input-output and economic indicators under different tillage and fertilizer cropping systems of corn, a split plot experiment in complete randomized design with three replications, was conducted at agricultural fields under Behbahan condition during 2015 and 2016. The experimental factors included different tillage systems (minimum (MT), reduced (RT) and conventional (CT)) as main plots and fertilizer patterns (bio fertilizer (B), manure (E), recommended chemical fertilizer rate (H) and half of recommended chemical fertilizer (L), integrated bio fertilizer and chemical fertilizer (BL), integrated manure and chemical (EL), and integrated bio fertilizer and manure as subplots. Assessment of energy indicators evaluated based on the energy output-input ratio. Human labor, machinery, diesel oil, fertilizer and seed amounts were the inputs and yield values from different treatments considered as output. Energy equivalents were used for this estimation. Based on the energy equivalents of inputs and outputs, energy use efficiency, energy productivity, specific energy and net energy was calculated. The production costs of each treatment included the land value, water value, fertilizer, fuel, human labor and tillage.

The results indicated that the highest grain (10005Kg ha-1) and straw yields (8409 Kg ha-1) belonged to ELRT treatment. The current study demonstrated that MT and RT with BI and EI have significant effects on grain yield. The results of data analysis indicated that maximum and minimum input energy was 45886.7 and 28392.9 MJ ha-1 in ELCT and BMT treatments, respectively. The greatest contribution from total energy belonged to energy of machinery (10375.3 MJ ha-1) and human labor (5142.6 MJ ha-1) in ELCT treatment. Highest and lowest energy of fertilizer belonged to EL (11762.2 MJ h-1) and B(5.96MJ ha-1), respectively. The input of energy for seed and irrigation water in all treatments was same (519 and 20016.7 Mg ha-1 , respectively) ELRT and BCT treatments produced the highest and lowest output energy with 309459.5 and 178965 Mg ha-1. The BMT provided the highest energy use efficiency (8.59), energy productivity (0.28 Kg Mg-1). Maximum specific energy (32.64MJ ha-1) belonged to BECT. ELRT and LCT produced the highest (266051 MJ ha-1) and the lowest (145119 MJ ha-1) net energy. Among different tillage systems, the highest energy use efficiency (7.42), and productivity energy (0.24 Kg Mg-1), net energy (225622 Mg) were calculated in MT.Economic analysis indicated that maximum and minimum total cost of production were 44288247.5 and 32097340 Rials ha-1 that related to ELCT and BMT treatments, respectively. The highest (113750572 Rials ha-1) and lowest (64987312 Rials ha-1) gross value were obtained ELRT and BCT, although maximum (69810430 Rials ha-1) and minimum (31400201Rials ha-1) net revenue was calculated ELRT and LRT respectively.

Application of minimum and reduced tillage, bio fertilizer and manures and integration with half of recommended chemical fertilizer, are the effective strategy to improve resource management in agriculture. Moreover, effective energy use in agriculture is one of the conditions for sustainable agricultural production, since it provides financial saving, fossil resources preservation and air pollution reduction.