Agriculture Strategy

Use of nitrogen-fixing fodder and cultivating green manure

Crop and country

Cultivation of maize in Spain and rice in India, Indonesia and Philippines. (Tejada et al. 2008); (Ali 1999).

Costs

Costs varied depending on methods and country. Rice straw use (for green manure) costs ranged from US$ 18/ha in Indonesia and Philippines, to US$ 40/ha in India. Azolla (type of fern) for nitrogen fixing and green manure meant additional costs ranging from US$ 34/ha in India, to US$ 48/ha in the Philippines.

No-tillage practices

Maize in Mexico, wheat in Morocco and cereal grain crop in England. (Erenstein et al. 2008); Mrabet et al. 2001; Baker 2007). Sorghum and maize in Botswana, (Panin 1995) Maize, sorghum and cowpea in Nigeria, (Eziakor 1990). Soybean in Australia (Grabski et al. 2009).

Biochar use

Cultivation of maize intercropped with soybean (Colombia) and wheat (USA). (Major et al. 2010; Galinato et al. 2010).

The capital costs for a small scale No-tillage planting system are estimated to be US$ 25,000 to 50,000 (ICARDA). No tillage system was cheaper by US$ 156/ha when rented from a contractor in England, compared to renting tilling systems. In Botswana, cost per household of tractor was US$ 218.

Biochar production costs range between US$ 87-350/tonne depending on source of inputs and mode of production.

Benefits

Maize crop yields increased approximately 40% in the first year, 5% in second year and 20% in year three. No significant increases in yields were observed in rice crops compared to the use of inorganic fertilisers but result in long term soil improvements. Maize crop yields increased after the first year, by 28%, 30% and 140% in the last 3 years of the study. No impact was seen on soybean crop yields.

Maize yields increased by 29 per cent; wheat yields by 44 per cent. No impact on total cultivated areas, crop yields and total crop output in traditional tillage systems vs. animal power or manual usage (Botswana and Nigeria). An average yield increase in soybean yields of 27% over 14 years in no-tillage vs. till systems.

Maize crop yields increased after the first year, by 28%, 30% and 140% in the last 3 years of the study. No impact was seen on soybean crop yields.

Table 3: Selected evidence on benefits and costs of soil management strategies

using tilling machinery, in developing countries the investment in farm equipment may represent a significant barrier. Farmer cooperatives and extension services can help defray these costs.

Biochar usage represents a costly investment, mainly because of the high cost of production for biochar (US$ 87-350 per tonne depending on the source of inputs and mode of production). Although it can bring significant increases in crop yields, biochar profitability is still highly dependent on the cost of production.

Similarly, the use of water for irrigation is rapidly exceeding the natural hydrological rate of recharge in many river basins (Johansson et al. 2002; WWAP 2003; Wani et al. 2009). Practices such as flooding fields, poor drainage and excessive pumping imply that there are many opportunities for using ground and rainwater in more efficient and sustainable ways (Steinfeld et al. 2006). Some sustainable water-use strategies include drip irrigation systems, pressurised water pipe and sprinkler systems and use of manual treadle pumps. According to some studies (Burneya et al. 2009; Sivanappan 1994; Belder et al. 2007), drip irrigation has resulted in yield gains of up to 100 per cent, and water savings of 40 to 80 per cent.

Using leaf and straw mulch reduces surface evaporation and helps to retain moisture near plant roots, thus increasing water-use efficiency (Sharma et al. 1998). Landscape contouring and vegetative barriers are an effective means of minimising rainfall runoff and retaining moisture in fields. Using drought-resistant varieties of crops can also help conserve water. For example, System Rice Intensive (SRI) practices substantially reduce the amount of water and other external inputs through decreased planting densities, which require less seed and fewer workers. The approach generally achieves between 40 per cent and 200 per cent greater crop yields compared with conventional flooded rice cultivation (Zhao 2009). Table 4 demonstrates that most water-saving technologies can bring about increased profits despite additional infrastructure and operating costs. Most water-saving techniques require additional equipment and increased working capital to cover the costs of increased labour use. Additional labour is required for strategies such as the use of mulching fields, raising plant beds and aligning furrows, and in other land contouring strategies. Such labour costs are nevertheless easily recovered through increased crop yields, and the reduced risk of losses during drought or dry years.

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Trends in revenues and profits after including additional costs of greening

Revenues increased even though there was no difference in the costs of using green manure over inorganic fertiliser for rice crops.

No-tillage systems are economically profitable, even after incorporating the costs of no-till systems. (Baker 2007).

In the US, wheat production increased sufficiently to generate a profit of US$ 414/ acre, but only while using low-price biochar. Higher-cost biochar reduces profits.