Water consumption, grain yield, and water productivity in response to field water management in double rice systems in China
and water productivity in response to field water
management in double rice systems in China.
PLoS ONE 12(12): e0189280. https://doi.org/
10.1371/journal.pone.0189280
Water consumption, grain yield, and water productivity in response to field water management in double rice systems in China
Xiao Hong Wu 0 1
Wei Wang 1
Chun Mei Yin 1
Hai Jun Hou 1
Ke Jun Xie 1
Xiao Li Xie 1
0 Faculty of Life Science and Technology, Central South University of Forestry and Technology , Changsha, Hunan , China , 2 Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences , Changsha, Hunan , China , 3 Hunan Agricultural Resources and Environmental Protection Management Station , Changsha, Hunan , China
1 Editor: Manuel JoaquÂõn Reigosa, University of Vigo , SPAIN
Rice cultivation has been challenged by increasing food demand and water scarcity. We examined the responses of water use, grain yield, and water productivity to various modes of field water managements in Chinese double rice systems. Four treatments were studied in a long-term field experiment (1998±2015): continuous flooding (CF), floodingÐmidseason dryingÐflooding (F-D-F), floodingÐmidseason dryingÐintermittent irrigation without obvious standing water (F-D-S), and floodingÐrain-fed (F-RF). The average precipitation was 483 mm in early-rice season and 397 mm in late-rice season. The irrigated water for CF, F-D-F, F-D-S, and F-RF, respectively, was 263, 340, 279, and 170 mm in early-rice season, and 484, 528, 422, and 206 mm in late-rice season. Grain yield for CF, F-D-F, F-D-S, and F-RF, respectively, was 4,722, 4,597, 4,479, and 4,232 kgha-1 in early-rice season, and 5,420, 5,402, 5,366, and 4,498 kgha-1 in late-rice season. Compared with CF, F-D-F consumed more irrigated water, which still decreased grain yield, leading to a decrease in water productivity by 25% in early-rice season and by 8% in late-rice season. Compared with F-DF, F-D-S saved much irrigated water with a small yield reduction, leading to an increase in water productivity by 22% in early-rice season and by 26% in late-rice season. The results indicate that CF is best for early-rice and FDS is best for late-rice in terms of grain yield and water productivity.
Data Availability Statement; All relevant data are within the paper
Introduction
Rice (Oryza sativa L.) is planted annually on areas of about 154 million hectares, taking up
about 11% of the world's cultivated land [
1
]. In fact, 90% of rice is grown in Asia, which
consumes about 80% of the total irrigated fresh water resources around the world [1±2]. Water for
agricultural use becomes increasingly scarce due to climate change and rapid industrialization
and urbanization [3±5]. By the year 2025, irrigated rice of 15±20 million hectares in Asia will
suffer water scarcity [
6
]. Farmers are facing a challenge to produce more rice per unit land
with limited water in order to meet the food demand of the growing population. This is crucial
and analysis, decision to publish, or preparation of
the manuscript.
for food security in many Asian countries where large and dense populations depend on
subsistence agriculture [7±10]. China is an important rice producer in Asia. From 2004 to 2014,
the total rice production in China increased from 180 million tons to 208 million tons, with
per unit area yield increasing from 6,308 kg ha-1 in 2004 to 6,811 kg ha-1 in 2014. However, the
population in China has increased from 1.36 billion to 1.44 billion during the same period.
Water is essential for growth and development of rice plants. However, continuous flooding
results in a large amount of unproductive water outflows through evaporation, seepage, and
percolation [11±13]. Growing evidence indicates that continuous flooding is unnecessary for
rice to achieve high yields, which, however, is based on short-term trials. Long-term field
water conditions would produce profound changes in soil properties, which may further affect
soil water conservation and crop yield. However, few studies have been conducted on
longterm field trial. So, there is little information on water consumption, crop yield, and water
productivity after long-term adoption of water-saving irrigation.
Rice agriculture occupies 23% of cultivated land in China [
14
], mostly distributed in the
south. Since fresh water distribution is distributed unevenly both spatially and temporally,
most farmers try to reserve rainwater in the field as much as possible unless when significantly
negative impacts occurred due to deep water. When the soil dries to a certain threshold,
farmers begin to irrigate the soil so that it is flooded or saturated. Rice is also grown traditionally
under rain-fed conditions, mainly due to lack of access to irrigation. Currently, typical modes
of water management include continuous flooding, floodingÐmidseason dryingÐflooding,
floodingÐmidseason dryingÐintermittent irrigation, and flood (...truncated)