Improving Biodiversity in Rice Paddy Fields to Promote Land Sustainability

Dermiyati and Ainin Niswati

Abstract Rice is a staple food for many people in the world, especially in Asian countries, and rice consumption increases every year. Efforts have been made to increase rice production, leading to social, economic, and environmental impacts. Rice in paddy fields is mostly grown using conventional farming systems with high inputs of agrochemicals (inorganic fertilizers and chemical pesticides). Continuous application of agrochemicals may damage the soil and cause decreased soil productivity and biodiversity, as well as increased pest attacks and methane emissions. Therefore, organic farming systems are likely to be the best practices for promoting land sustainability. In fact, farmers in many countries have shifted their rice production management from conventional to organic. However, it is argued that, in general, organic systems are related to lower yields and lower environmental impacts while conventional systems are related to higher yields and higher environmental impacts. Although the movement from conventional to organic farming systems is believed to have positive short-term impacts by improving soil biodiversity, therefore, it will also have an impact in terms of lowering rice production volumes. The achievement of food security and food availability requires government policies to promote the use of organic fertilizers and subsidize their prices, as well as regulation to support high prices for organic products. Application of organic fertilizers and biofertilizers, and the use of crop rotation, are likely to improve soil fertility, which is related to increased biodiversity, and eventually this will contribute to higher rice production volumes in the long term.

Keywords Biodiversity in rice paddy fields • Conventional and organic farming • Soil biodiversity

Introduction

Various types of organisms live in wetland rice and each of them interacts with others to form a specific food chain (Ali 1990; Roger et al. 1993). The direct or indirect effect of one organism on another will affect the community structure of the wetland rice organisms, which consist of nematodes, microcrustacea, protozoa, insect larvae, algae, mollusca, and oligochaetae (Mogi 1993). As the organisms interact with each other, their populations are also affected by environmental factors, including fertilizer and pesticide application, water management, and crop variety (Simpson et al. 1994).

The role and potential of microorganisms and invertebrates in biodiversity and sustainability of wetland rice production has been reviewed by Roger et al. (1991). Suitable rice-producing environments are essential for wetland rice production. It is therefore important to consider microorganisms and invertebrates as well as their biodiversity in wetland rice. Sustainable rice-producing environments depend on microbial and invertebrate populations, agricultural practices, the status of germplasm collection, and developments in biotechnology.

Moreover, whilst crop intensification using agrochemicals does increase yields, on the other hand it also reduces the number of edible species traditionally harvested from ricefields, such as snails, prawns, crabs, large water bugs, fish, and frogs (Heckman 1979). Agrochemicals also cause uncontrolled growth of single species that might, directly or indirectly, have detrimental effects, such as the outbreak of pests (Heinrichs 1988). In addition, fertilityor health-related aspects of ecosystems may be affected by other organisms, such as: (1) blooms of unicellular algae (observed after fertilizer application, which causes nitrogen losses by volatilization);

(2) proliferation of ostracods and chironomid larvae (observed after insecticide application, which inhibits the development of efficient nitrogen-fixing blue-green cyanobacterial blooms); and (3) proliferation of snails or mosquito larvae (observed after insecticide application, which causes vector-borne diseases) (Roger and Kurihara 1988).

Nowadays, rice is generally cultivated in two forms: conventional and organic. In Indonesia, however, some farmers choose to follow a middle course, known as “semi-organic.” Many reports suggest that organic agriculture is more efficient, and also effective in reducing water and soil pollution (Erhart and Hartl 2009), greenhouse gas emissions (Lumbaraja et al. 1998), and risks to human health (Mader et al. 2002), as well as increasing energy efficiency (Mansoori et al. 2012). Research was conducted in Iran on the relative energy efficiency and economic benefits of organic versus conventional rice production. The organic farms performed better than conventional rice production systems in terms of all energy efficiency indexes, as well as cost-to-benefit ratios and gross and net returns, while total costs of production were also lower (Mansoori et al. 2012). Previously, Lumbaraja et al. (1998) had studied methane emissions from Indonesian rice fields in several locations in Sumatra and Bali. They found that methane emissions in rain-fed conditions were 27–37 % lower than in continuously flooded conditions. In separate research, it was noted that paddy fields contribute about 10 % of all global methane emissions (Oyewole 2012).

This chapter considers the sustainability of rice production when shifting from conventional to organic farming systems according to Indonesian experiences. It focuses especially on paddy fields containing microbial and invertebrate populations.

 
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