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8.1 Introduction
Rice straw management after harvest is an important component of the rice production cycle, particularly in Asia where 90% of the world’s rice is produced, and,
consequently, where the bulk of the straw is produced. Traditionally in Asia, rice is
manually harvested by cutting and carrying to a central threshing location for separation of grain and straw, with only a small portion of straw retained in the field.
Straw was considered a waste product and was either burned or used for other purposes such as fodder or animal bedding. However, the increasing use of combine
harvesters in the region has resulted in large amounts of rice straw being left in field.
The in-situ incorporation of rice straw in the soil has been shown to contribute to
recycling of nutrients and increasing soil organic carbon (C) and yields of subsequent crops (Bijay-Singh et al. 2004; Gupta et al. 2007).
While rice straw contains significant amounts of nutrients, its incorporation into
the soil is labor-intensive and affects seedbed preparation and crop establishment.
This makes land preparation expensive compared to the common practice of openfield burning. On the other hand, straw burning releases particulate matter into the
atmosphere, which is associated with air pollution and human respiratory ailments.
This has led to bans on open-field straw burning in most major rice-producing countries, although such policies have been largely difficult to enforce. The production
of two or three rice crops annually results in the production of large quantities of
straw, with little turnaround time between crops, particularly where three crops are
grown annually. This results in limited decomposition of the straw when incorporated, with potential negative effects on nutrient availability and use efficiency of
applied fertilizers for the subsequent crop (Bijay-Singh et al. 2004; Dobermann and
Fairhurst 2000). Depending on the type of water management following straw
incorporation, greenhouse gas emissions (GHEs) can also increase (Sander
et al. 2014).
Large amounts of rice straw left in the field have posed challenges in ricegrowing areas because of the need for mechanization and multiple tillage operations
to enable effective incorporation of the straw into the soil. Similarly, the adoption of
no-till in rice-cropping systems has been limited by the presence of the large
amounts of straw on the soil surface where combine harvesters are used. However,
equipment innovations have been developed, such as the Happy Seeder, to enable
direct seed drilling while cutting the standing stubble into mulch (Sidhu et al. 2007).
Straw incorporation, nonetheless, benefits the next crop and ecosystem services, in
general, depending on management practices and the cropping system employed.
Incorporating straw in rice fields serves as a source of food for an array of fauna that
use rice fields as a habitat. For example, Schmidt et al. (2015) noted that rice straw
provides substrate to promote biodiversity through flourishing of invertebrates that
decompose the straw, which in turn enhances nutrient cycling in paddy soils. This
chapter provides information on the benefits and challenges associated with incorporating rice straw into the soil, including alternative forms through which rice
straw can be used as a soil amendment.
P. Chivenge et al.
8.1 Introduction
Rice straw management after harvest is an important component of the rice production cycle, particularly in Asia where 90% of the world’s rice is produced, and,
consequently, where the bulk of the straw is produced. Traditionally in Asia, rice is
manually harvested by cutting and carrying to a central threshing location for separation of grain and straw, with only a small portion of straw retained in the field.
Straw was considered a waste product and was either burned or used for other purposes such as fodder or animal bedding. However, the increasing use of combine
harvesters in the region has resulted in large amounts of rice straw being left in field.
The in-situ incorporation of rice straw in the soil has been shown to contribute to
recycling of nutrients and increasing soil organic carbon (C) and yields of subsequent crops (Bijay-Singh et al. 2004; Gupta et al. 2007).
While rice straw contains significant amounts of nutrients, its incorporation into
the soil is labor-intensive and affects seedbed preparation and crop establishment.
This makes land preparation expensive compared to the common practice of openfield burning. On the other hand, straw burning releases particulate matter into the
atmosphere, which is associated with air pollution and human respiratory ailments.
This has led to bans on open-field straw burning in most major rice-producing countries, although such policies have been largely difficult to enforce. The production
of two or three rice crops annually results in the production of large quantities of
straw, with little turnaround time between crops, particularly where three crops are
grown annually. This results in limited decomposition of the straw when incorporated, with potential negative effects on nutrient availability and use efficiency of
applied fertilizers for the subsequent crop (Bijay-Singh et al. 2004; Dobermann and
Fairhurst 2000). Depending on the type of water management following straw
incorporation, greenhouse gas emissions (GHEs) can also increase (Sander
et al. 2014).
Large amounts of rice straw left in the field have posed challenges in ricegrowing areas because of the need for mechanization and multiple tillage operations
to enable effective incorporation of the straw into the soil. Similarly, the adoption of
no-till in rice-cropping systems has been limited by the presence of the large
amounts of straw on the soil surface where combine harvesters are used. However,
equipment innovations have been developed, such as the Happy Seeder, to enable
direct seed drilling while cutting the standing stubble into mulch (Sidhu et al. 2007).
Straw incorporation, nonetheless, benefits the next crop and ecosystem services, in
general, depending on management practices and the cropping system employed.
Incorporating straw in rice fields serves as a source of food for an array of fauna that
use rice fields as a habitat. For example, Schmidt et al. (2015) noted that rice straw
provides substrate to promote biodiversity through flourishing of invertebrates that
decompose the straw, which in turn enhances nutrient cycling in paddy soils. This
chapter provides information on the benefits and challenges associated with incorporating rice straw into the soil, including alternative forms through which rice
straw can be used as a soil amendment.
P. Chivenge et al.