Biofuels, Solar and Wind as Renewable Energy Systems_Benefits and Risks Episode 2 Part 9 pps

17 Organic and Sustainable Agriculture and Energy Conservation 441

climatic variability, providing soil and crop characteristics that can better buffer

environmental extremes, especially in developing countries.

However, it has to be pointed out that local specificity plays an important role in

determining the performance of a farming system: what is sustainable for one region

may not be for another region or area (Smolik et al., 1995). So, more work has to

be done to acquire knowledge about the comparative sustainability of other farming

systems.

17.2.1.2 Organic Farming for Developing Countries

Energy and economic savings from organic farming can offer an important opportu￾nity for developing countries to produce crops with limited costs and environmental

impact. Some authors claim that organic farming can reduce food shortage by in￾creasing agricultural sustainability in developing countries, contributing quite sub￾stantially to the global food supply, while reducing the detrimental environmental

impacts of conventional agriculture (Netuzhilin et al., 1999; Paoletti et al., 1999;

Pretty and Hine, 2001; FAO, 2002; Pretty et al., 2003; Badgley et al., 2007). Pretty

and Hine (2001) surveyed 208 projects in developing tropical countries in which

contemporary organic practices were introduced, they found that average yield

increased by 5–10% in irrigated crops and 50–100% in rainfed crops. However,

those claims have been challenged by different authors (e.g. McDonald et al., 2005;

Cassman, 2007; Hudson Institute, 2007; Hendrix, 2007), who dispute the correct￾ness of both the accounting and comparative methods employed. Hudson Insti￾tute (2007) refers that in most of the farming cases accounted as organic by Pretty

and Hine (2001) chemical fertilisers and/or pesticides have been regularly applied.

The latter may be a sound observation. However, we argue that the amount of inputs

employed plays a critical role in maintaining the long term sustainability of farming

systems. So, although the “organic certification” cannot apply to a farm which uses

pesticides, we should recognise the effort to keep the amount at a minimum and the

use stack to the real needs. We should aim at is of reducing as much as possible

our impact. In this sense organic farming is paving the way to gain knowledge and

experience about best practices making them available to all.

17.2.2 A Trade off Perspective

In order to gain an useful insight on the sustainability of a farming system differ￾ent criteria such as land, time and energy, should be employed at the same time

(Smil, 2001; Giampietro, 2004; Pimentel and Pimentel, 2007a). Data on energy

efficiency cannot be de-linked from total energy output and from the metabolism

of the social system where agriculture is performed. Great energetic efficiency may

implie low total energy output that for a large society with limited land may not be

a sustainable option menacing food availability.

Models for energy assessment for Danish agriculture developed by Dalgaard

et al., (2001), to compare energy efficiency for conventional and organic agriculture,

442 T. Gomiero, M.G. Paoletti

were used to evaluate energy efficiency for eight conventional and organic crop

types on loamy, sandy, and irrigated sandy soil. Results from the model indicated

that energy use was generally lower in the organic than in the conventional system

(about 50%), but yields were also lower (about 40–60%). Consequently, conven￾tional crop production had the highest energy expenditure production, whereas or￾ganic crop production had the highest energy efficiency. The same results have been

produced also by Cormack (2000) for the UK, modelling a whole-farm system using

typical crop yields. (However, it has to be said that in some long term trials yield

difference for some crops, in terms of ton/ha, between organic and conventional

crops has been minimal or negligible; e.g. Reganold et al., 2001; Delate et al., 2003;

Vasilikiotis, 2000; Pimentel et al., 2005).

This inverse relation between total productivity and efficiency seems typical for

traditional and intensive agriculture. When comparing corn production in intensive

USA farming system and Mexican traditional farming system it resulted that the

previous had an efficiency (output/input) of 3.5:1 while the latter of 11:1 (using

only manpower). However, when coming to total net energy production, intensive

farming system accounted for 17.5 million kcal/ha yr−1(24.5 in output and 7 in

input), while traditional just 6.3 million kcal/ha yr−1 (7 million in output and 0.6

million in input) (Pimentel, 1989).

In Europe, the yield from arable crops was 20–40% lower in organic systems and

the yield from horticultural crops could be as low as 50% of conventional. Grass and

forage production was between 0% and 30% lower (Stockdale et al., 2001; Mader ¨

et al., 2002). This led Stockdale et al. (2001) to conclude that when calculating the

energy input in terms of unit physical output, the advantage to organic systems was

generally reduced, but in most cases that advantage was retained.

The productivity of labour is another key indicator that has to be considered to

assess the socio-economic sustainability of the farming enterprise. Although per￾forming better in terms of energy efficiency, organic farms require more labour

Table 17.4 A comparison of the rate of return in calories per fossil fuel invested in produc￾tion for major crops – average of two organic systems over 20 years in Pennsylvania (based on

Pimentel, 2006a, modified)

Crop Technology Yield

(t/ha)

Labour

(hrs/ha)

Energy (kcal

x 106)

kcal (out￾put/input)

Corn Organic1 7.7 14 3.6 7.7

Corn Conventional2 7.4 12 5.2 5.1

Corn Conventional3 8.7 11.4 8.1 4.0

Soybean Organic4 2.4 14 2.3 3.8

Soybean Conventional5 2.7 12 2.1 4.6

Soybean Conventional6 2.7 7.1 3.7 3.2

1 Average of two organic systems over 20 years in Pennsylvania

2 Average of conventional corn system over 20 years in Pennsylvania

3 Average U.S. corn.

4 Average of two organic systems over 20 years in Pennsylvania

5 Average conventional soybean system over 20 years in Pennsylvania

6 Average of U.S. soybean system