Technologies and Strategies

There are a number of technologies and strategies that could help reduce the vulnerability of agriculture and forestry to climate variability and climate change. Stigter et al. (2005) referred to the fact that countless farming communities managed to survive and, in some cases, even to thrive by exploiting natural resource bases which their forebears have used for generations. Through a process of innovation and adaptation, indigenous farmers have developed numerous different farming systems finely tuned to many aspects of their environment.

Traditional knowledge, indigenous practices and identified local innovations contain valuable information that should be used as a basis for improved technologies and strategies to cope with projected changes. Climate variability and related disasters can be mitigated by temporary or permanent protective measures or by avoidance strategies that try to escape the peak values or their consequences. These are all aspects of preparedness strategies.

As Stigter et al. (2005) explained, in the context of climate change, traditional knowledge and indigenous technologies that mitigate consequences of variabilities of (i) heavy moisture flows or the lack of water, (ii) changing heat flows and related temperatures, (iii) and cropping seasons need special attention. Drought being already a serious threat, indications for longer dry spells in rainy seasons and longer sequences or higher frequencies of abnormal rainfall seasons, with respect to total rainfall and rainfall distribution, make the indigenous ways of coping with drought situations even more important.

One of the popular indigenous technologies described by Stigter et al. (2005) is traditional water harvesting methods and technologies of the use of underground water. A related technology of which also the IPCC advocates more intensive use is that of water impoundment. Several useful examples are given from Indonesia, Sri Lanka, Niger, and Burkina Faso. Permaculture, water harvesting and infiltration pits, together with the use of drought tolerant crops, have been more recently extended in Zimbabwe, particularly by women, with the help of NGOs, in reply to the recurrent droughts.

Many of the same traditional adaptation strategies with agrometeorological components that we presently try to apply also hold for the situations of increasing climate variability and Stigter et al. (2005) present evidence from China to substantiate this fact.

Response farming evolved as a promising technology in the past two decades to alter cropping systems/cropping patterns in relation to fluctuations in seasonal weather. Stigter et al. (2005) suggest that response farming should not only be considered with respect to fitting the cropping seasons to variable rainfall patterns but also for fitting it to variable temperature patterns. They cite the case study from Vietnam (Van Viet, 2001) where either planting date or a combination of planting date and variety could be varied, to make sure that rice was flowering in decades for which the required optimal temperatures had been forecasted. For example the detailed knowledge available on the influence of temperature, temperature extremes and temperature distributions on growth, development and yield of rice (Salinger et al., 1997) makes this possible.

Where temperature is a limiting factor to photosynthesis, traditional farmers may react to cooling/warming by changing their cropping system. Stigter et al. (2005) give the example of changing cropping patterns from North China Plain.

They also give relevant examples of microclimate management and manipulation to cope with temperature changes, e.g., parkland agroforestry and other stabilizing intensive management of scattered or clumped or alleyed trees.

One promising new technology that offers much promise is the application of seasonal to interannual climate forecasts. Disaster preparedness strategies, both of governments and NGOs, have begun to take account of such forecasts, and there is considerable interest in assigning them an economic value. The challenge of course is to reduce the gap between the information needed by small scale farmers and that provided by the meteorological services (Blench, and Marriage 1998; Lemos et al., 2002). As Stigter et al. (2005) noted, low-income farmers are interested in a broader range of characteristics of precipitation, notably, total rainfall, patchiness of rainfall, intensity, starting date, distribution of rainfall, end of the rains and prospects for dry spells and their length. It is precisely in this area that scientific extensions and improvements of response farming approach would bring highly needed solutions (Stewart, 1988). Demonstration projects such as the CLIMAG (Climate Prediction and Agriculture) project currently being implemented in South Asia and West Africa could provide useful information for implementation of similar pilot projects in other regions.

The substantial losses in soil C due to anthropogenic activities have prompted a great deal of interest in the recent past in the concept that agricultural lands have the potential to regain some of this C and that globally between 0.4 and 0.8 Pg / Yr of C could be sequestered in agricultural soils for 50 to 100 yr through good soil management.

Desjardins et al. (2005) discussed a number of agricultural land management practices that have shown potential for increasing C content in agricultural soils. Adoption of permanent cover is one of these practices. Converting cropland into perennial forage may result in a substantial increase in C sequestration. Prevention of overgrazing is also a mitigation strategy that can improve soil carbon levels in pastures significantly.

Conservation tillage or no-till management, when combined with the use of cover crops, proper crop rotations, fertilizer strategies and manure applications, is one of the most efficient practices for sequestering C in cropland.

Reduction of summer fallow in crop rotations which results in greater cropping intensity will increase crop production and thus increase C inputs to soil and increase soil organic carbon. This will also increase water use, keeping soils dryer longer and thus reduce soil decomposition.

Most studies have shown a consistent contribution of forages to soil carbon sequestration. Perennial grasses or legumes in rotation, high yielding varieties and soil management practices that permit the return of large amounts of crop residues to the soil can potentially increase soil organic matter, thus increasing the likelihood for sequestering atmospheric CO2. The use of legumes in crop rotations can also appreciably reduce the requirements for N fertilizers for various cropping systems, thereby reducing net fossil fuel use during manufacturing of N fertilizers.

Desjardins et al. (2005) also referred to the fact that most agricultural ecosystems are nitrogen-limited. Adding N fertilizer usually results in increased crop production and may therefore increase C sequestration in soils. However, in considering the net effect on the GHG budget, it is important to take into account the fact that nutrient additions via fertilizer can lead to higher N2O emissions and may also tend to reduce the CH4 uptake by soils. Further, there is C emitted in the manufacturing and transportation of N fertilizer that must also be accounted for.

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