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Environment, Development and Sustainability
https://doi.org/10.1007/s10668-024-04495-8
1 3
Effects ofirrigated anddryland conditions onenergy indices
inwheat production: ameta‑analysis based ontheprincipal
components analysis
AbolfazlNasseri1
Received: 21 August 2022 / Accepted: 10 January 2024
© The Author(s), under exclusive licence to Springer Nature B.V. 2024
Abstract
Irrigated and dryland production systems have different production inputs and energy indi-
ces in the farms. The previous studies compared only some energy indices from mentioned
conditions with limited or locally applicable findings. Now, meta-analysis is applied to
summarize, merge and combine findings and results of independent and repeated agro-
nomic studies. Also, a powerful technique known as principal component analysis (PCA)
is applied to convert a large number of correlated indices into a smaller number called
principal components. A meta-analysis based on the PCA was conducted by collecting and
investigating the data published in peer-reviewed papers to classify the major indices; and
to evaluate the effect of irrigated conditions in comparison with the dryland one on energy
indices in wheat farms. The PCA revealed that the first two components (PC1 and PC2)
described about 80% of the data-variations of energy indices for both irrigated and dryland
treatments. Energy indices were divided into homogenous clusters based on the contribu-
tions to principal components. The indices of the first cluster (net energy gain and energy
output) had the most considerable contribution to principal components. The meta-analysis
of 628 observations on energy indices and production inputs showed that irrigation prac-
tice significantly increased grain yield by 142%, energy input by 120%, energy output by
133%, and net energy gain by 152% compared with dryland conditions. Moreover, irriga-
tion practice with average applied water of 4134 (m3 ha−1) had higher consumption energy
in human labor (118%), machinery (67%), nitrogen fertilizer (85%), fuel (61%), seed (43%)
and herbicides (116%) compared with dryland conditions. The regression analysis among
energy indices and production inputs showed that an increase in human labor, machinery,
fuel, irrigation, herbicides and wheat grain yield caused an increase in energy input, net
energy and energy output from farms. Some strategies, including the appropriate applica-
tion of agronomic practices, were suggested to reduce the negative impact of energy input
and to improve both yield and energy indices in dryland and irrigated wheat production.
* Abolfazl Nasseri
nasseri.ab@gmail.com
1 Agricultural Engineering Research Department, East Azarbaijan Agricultural andNatural
Resources Research andEducation Center, AREEO, Tabriz, Iran
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