Using aquatic animals as partners to increase yield and maintain soil nitrogen in the paddy ecosystems

Abstract

Whether species coculture can overcome the shortcomings of crop monoculture requires additional study. Here, we show how aquatic animals (i.e. carp, crabs, and softshell turtles) benefit paddy ecosystems when cocultured with rice. Three separate field experiments and three separate mesocosm experiments were conducted. Each experiment included a rice monoculture (RM) treatment and a rice-aquatic animal (RA) coculture treatment; RA included feed addition for aquatic animals. In the field experiments, rice yield was higher with RA than with RM, and RA also produced aquatic animal yields that averaged 0.52–2.57 t ha-1. Compared to their corresponding RMs, the three RAs had significantly higher apparent nitrogen (N)-use efficiency and lower weed infestation, while soil N contents were stable over time. Dietary reconstruction analysis based on 13C and 15N showed that 16.0–50.2% of aquatic animal foods were from naturally occurring organisms in the rice fields. Stable-isotope-labeling (13C) in the field experiments indicated that the organic matter decomposition rate was greater with RA than with RM. Isotope 15N labeling in the mesocosm experiments indicated that rice used 13.0–35.1% of the aquatic animal feed-N. All these results suggest that rice-aquatic animal coculture increases food production, increases N-use efficiency, and maintains soil N content by reducing weeds and promoting decomposition and complementary N use. Our study supports the view that adding species to monocultures may enhance agroecosystem functions.

Commercialization, Voodoo Ritual, and Use of the Endangered Hispaniolan Slider, Trachemys decorata, in Haiti: Implications for Conservation

“…First, most farmers in Haiti do not use agrochemicals to improve their production, simply because they cannot afford to buy the few products that are available on the market (Bargout and Raizada 2013; Moya et al 2019; Severe et al 2019). Second, rice-aquatic animal co-culture is precisely a cost-effective way of increasing food production and soil fertility without resorting to agrochemical products (Zhang et al 2016; Wu et al 2021; Guo et al 2022; Li et al 2022). Improved rice production could then act to reduce the country's import bill and strengthen national earnings.…”

Sustainable Blue Foods from Rice–Animal Coculture Systems

“…8 Animals' activities in the paddies help loosen soils, ventilate, and oxygenate water, thus altering the on-site CH 4 and N 2 O emissions, while the feces excreted by animals provide nutrients for rice growth, thus reducing fertilizer use (Figure 1). Compared with rice monocultures, coculture systems have been shown to bring greater economic profits, 9 reduce rice diseases, weeds, and insect pests, 10 use less fertilizer and pesticide inputs, 11,12 and emit lower GHG emissions. 13 T h i s c o n t e n t i s While there have been some local, life cycle studies of these coculture systems, 6,14,15 their results are hardly representative given the spatial variability in emissions and resource use.…”

Spatial distribution of soil nutrient content for sustainable rice agriculture using geographic information system and Naïve Bayes classifier

“…The quality of the food consumed is influenced by several factors, such as the weather, the content of natural chemical compounds in the food, and the water quality [7], [8], [10], [11]. Rice plants grow excellently in ecosystems having areas with availability of abundant water for irrigation and huge amounts of water vapor [7], [12]. Around 0-1500 mesh is suitable for the rice plant ecosystem [13].…”