S. K. Guru
6.4 Biotechnology for climate change mitigation Biotechnology plays a great role in reducing the on-farm fuel
food insecurity, hunger and malnutrition, particularly in South Asia and sub-Saharan Africa (Nelson et al., 2009; Parry et al., 2009). For example, the global temperature increased between 1981 and 2002, reducing the yields of major cereals by cost- ing as much as $5 billion per year (Lobell and Field, 2007).
The productivity of maize was drastically reduced by heat waves and drought in Italy (Ciais et al., 2005). Heat waves also affected wheat production in Central Asia and extreme flood- ing in South Asia in 2009–2010. In addition to the challenges associated with the climate change like extreme temperatures, drought and flooding, the biotic stresses such as pests, diseases and alien weed species also affect the current cropping systems (Hyman et al., 2008; Wassmann et al., 2009).
6.3 Biotechnology for climate change mitigation
Biotechnology provides a valuable solution for reducing the amount of chemical fertilisers used in conventional farm- ing, finally leading to a reduction in the amount of greenhouse gases released into the atmosphere. This has been made pos- sible by the development and use of modern biotechnology such as genetically modified organisms (GMOs) that have low fer- tiliser input needs. For example, the rice and canola developed by Arcadia Biosciences are genetically modified (GM) to use nitrogen more efficiently, resulting in reduced fertiliser needs.
This technology, which is referred to as nitrogen use efficiency (NUE), allows farmers to produce yields equivalent to conven- tional agriculture without a significant requirement for nitro- gen fertilisers. Artificial inorganic nitrogenous fertilisers like ammonium sulphate, ammonium chloride, ammonium phos- phate, sodium nitrate and calcium nitrate are responsible for the formation and release of greenhouse gases (especially N2O) from the soil to atmosphere when they interact with common soil bacteria (Brookes and Barfoot, 2009). Additionally, improved NUE in crops leads to the lower emission of greenhouse gases in the atmosphere through reduced fertiliser application. The reduced input of nitrogen fertilisers also means less nitrogen pollution of ground and surface waters. The GMOs and other related technologies like organic farming also reduce on-farm fuel usage, leading to reduction in CO2 emissions, by decreas- ing the necessity and frequencies of spraying with fertilisers, pesticides and herbicides. Additionally, the GM crops will con- tinue to reduce greenhouse gas emissions through reduced fer- tiliser application by combining the initial CO2 reduction with further improvements in biotechnology research.
The use of environment-friendly biotechnology-based fer- tilisers (composted humus and animal manure) should be encouraged to reduce the negative effects of artificial fertilis- ers. Organic farming based on biofertilisers, crop rotation and intercropping with leguminous plants having nitrogen-fixing abilities are among some of the conventional biotechnologi- cal strategies for reducing artificial fertilisers use (Varshney et al., 2011). The use of genetically engineered techniques to improve Rhizobium inoculants led to the development of strains with improved nitrogen-fixing characteristics. The non-leguminous cereal crops, such as rice and wheat, can be made to fix nitrogen in the soil by inducing nodular structures on their roots using biotechnological approaches (Yan et al., 2008). Additionally, manipulation of animal diet and manure management can reduce CH4 and N2O emissions from animal husbandry (Johnsona et al., 2007). Agricultural biotechnology
should provide for solutions to fight against climate change. In this context, biofuels produced both from traditional and GMO crops, such as sugarcane, oilseed, rapeseed and jatropha, will play a crucial role in reducing the adverse effects of greenhouse gases emission, particularly CO2 by the transport sector. Hence, energy-efficient farming will depend on machines that use bio- ethanol and biodiesel instead of the conventional fossil fuels.
A plantation of perennial non-edible oil seed producing plants will help in clearing the atmosphere and producing biodiesel fuel for direct use in the energy sector or in blending biofuels with fossil fuel in certain proportion, thereby minimising the use of fossil fuels to some extent (Jain and Sharma, 2010).
The capture or uptake of the carbon-containing substances, particularly carbon dioxide, is often referred to as carbon sequestration. It is commonly used to describe any increase in soil organic carbon content caused by the change in land management (Powlson et al., 2011). The soil carbon sequestra- tion is one of the important strategies to limit the increase of the atmospheric CO2 concentration. One way to enhance carbon sequestration is by reducing conventional tillage. Conventional tillage means to completely turn the soil to reduce the need for weed control and receive higher yield. However, tillage causes high erosion rates, resulting in the release of CO2 into the atmo- sphere and the loss of other nutrients from soil. Tillage also increases the speed of decomposition of organic matter in the soil by increasing the availability of oxygen in the soil. An alter- nate approach to conventional tillage is the conservation tillage, which leaves approximately 30% of crop residue on the land to help reduce soil erosion from wind and rain. In this way, it reduces the loss of CO2 from the agricultural systems and also plays a vital role in reducing water loss through evaporation, increasing soil stability and in maintaining cool soil microcli- mate. Conservation tillage is considered the superior option to conventional tillage as it reduces erosion and sedimentation in nearby waterways and allows for more natural soil cycles.
Biotechnology takes conservation tillage a step further by cre- ating GM crops like herbicide-tolerant (HT) seeds that reduce the need for tillage and allow farmers to adopt ‘no-till’ farming practices. In no-till farming, crops are specifically designed to reduce the impacts of soil preparation through plowing, ripping or turning the soil. HT crops allow farmers to apply herbicides to the emerging weeds rather than incorporating into the soil through tillage. This strategy has been made possible only by the use of biotechnology, which allowed the development of GM seeds, in the absence of which herbicides would have killed both
the crops and the weeds. The main purpose of the herbicide- resistant plants is to reduce the need for tillage, finally providing protection to nearby environments through reduced erosion and enhanced soil sequestration. For example, the GM herbicide- resistant Round up ReadyTM soybean accounted for up to 95%
of no-till areas in the United States of America (USA) and in Argentina, leading to the sequestration of 63,859 million tonnes of CO2 (Kleter et al., 2008). HT crops allow farmers to kill only the weeds avoiding the greenhouse gas intensive process of weed control by traditional tillage, finally leading to more soil carbon sequestration. No-till agriculture, in addition to car- bon sequestration, reduces the consumption of fuel to operate equipment, thereby reducing CO2 emissions. The gross global warming potential (GWP) for no-till agriculture is drastically lower than both traditional and conservation tillage (Figure 6.2).
Reduction of fuel usage due to the application of biotechnol- ogy amounted to savings of about 962 million kg of CO2 emit- ted in 2005, while the adoption of reduced tillage or no-tillage practices led to the reduction of 40.43 kg/ha CO2 emissions due to less fuel usage, respectively. Therefore, in terms of carbon sequestration and reduced greenhouse gas emissions, it is clear that GM HT crops are beneficial for climate change mitigation.