Traditional rice-fish system benefits sustainable production of small farms and conservation of local resources

Abstract

CONTEXT

Small farms account for most of the world's farms (approximately 84 % of the world's farms are <2 ha in size). Helping smallholder farms achieve sustainable production is one the Sustainable Development Goals (SDGs). Worldwide, traditional agriculture has contributed to food and livelihood security of smallholder farms for centuries. The values of traditional agriculture in supporting sustainable production and in conserving local resources, however, has often been overlooked in science and policy making.

OBJECTIVE

Our objective is to examine whether and how traditional agriculture benefits sustainable production of smallholder farms and concomitantly conserving local resources.

METHODS

We performed the study in sites of the Globally/China-Nationally Important Agricultural Heritage System (i.e., rice-fish system, RF), which has been practiced by smallholders in southwestern China. Six counties that have a long history of rice-fish farming were included. We used a stratified sampling protocol with three strata (county, town, and village) in the field and farmer surveys, and in the sample collections. Sixteen towns and twenty-eight villages were sampled. ArcGIS (10.3.1) was used to estimate the sizes of the paddy field and farms. Data of yields were collected from farmer harvest. Field surveys were conducted to measure the depth of water layer in paddy fields and to collect samples of rice and fish. Shannon- Wiener's diversity index (H) was used to indicate rice variety diversity. Microsatellite DNA was used to evaluate genetic diversity of rice and fish (common carp, Cypinus carpio).

RESULTS AND CONCLUSION

Compared to rice monoculture (RM) smallholders, RF smallholders produced more stable rice yield but used fewer synthetic pesticides and fertilizers. RF smallholders obtained a certain quantity of fish yield from paddy fields, and had higher net income than RM smallholders. RF system in our study sites stored a large amount of rainwater during rainy season, and harbored diverse local rice varieties and indigenous common carp populations. Six morphotypes of indigenous common carp based on body coloration patterns and nomenclature assigned by local farmers were found in RF system. Shannon- Wiener's diversity index (H) of rice variety in RF system was higher than in RM system. Microsatellite DNA test further indicated that both local rice varieties and indigenous common carp exhibited high level of genetic diversity.

SIGNIFICANCE

Our results highlight the importance of traditional agricultural systems (e.g., rice-fish system) in enhancing sustainable production of smallholder farms and conservation of local resources. Recognizing the value of these traditional agricultural systems would help to boost support policies.