To use oil from plants might be still unimportant nowadays. But in the future such products may become as important as petroleum.

Rudolf Diesel — inventor of the Diesel engine, 1912.

5.1

Intercropping and Double Cropping

Intercropping is the practice of growing two or more crops in close proximity. The most common goal of intercropping is to produce a greater yield on a given piece of land by making use of resources that would otherwise not be utilized by a single crop. Careful planning is required, taking into account the soil, climate, crops, and varieties. It is particularly important not to have crops competing with each other for physical space, nutrients, water, or sunlight. Examples of inter­cropping strategies are planting a deep-rooted crop with a shallow-rooted crop, planting a tall crop with a shorter crop that requires partial shade, or planting a fast-growing crop with a slow-growing crop.

When crops are carefully selected, other agronomic benefits are also achieved. Lodging-prone plants (i. e., those that are prone to tip over in wind or heavy rain) may be given structural support by their companion crop. Delicate or light-sensitive plants may be given shade or protection, or otherwise wasted space can be utilized. An example is the tropical multitier system where coconut occupies the upper tier, banana the middle tier, and pineapple, ginger, or leguminous fodder, medicinal or aromatic plants occupy the lowest tier.

Intercropping of compatible plants also encourages biodiversity and fertility of the soil, by providing a habitat for a variety of insects and soil organisms that would not be present in a single-crop environment. This biodiversity can in turn help to limit outbreaks of crop pests by increasing the diversity or abundance of natural ene­mies, such as spiders or parasitic wasps. Increasing the complexity of the crop environment through intercropping also limits the places where pests can find optimal foraging or reproductive conditions.

Second Generation Biofuels and Biomass: Essential Guide for Investors, Scientists and Decision Makers, First Edition. Roland A. Jansen. r 2013 Wiley-VCH Verlag GmbH & Co. KGaA.

Published 2013 by Wiley-VCH Verlag GmbH & Co. KGaA.

The degree of spatial and temporal overlap in the two crops can vary somewhat, but both requirements must be met for a cropping system to be an intercrop. Numerous types of intercropping, all of which vary the temporal and spatial mixture to some degree, have been identified.

Some of the more significant types include:

• Mixed intercropping, as the name implies, is the most basic form in which the component crops are totally mixed in the available space. I have not seen this very often.

• Row cropping involves the component crops arranged in alternate rows. This may also be called alley cropping. A variation of row cropping is strip cropping, where multiple rows, or a strip, of one crop are alternated with multiple rows of another crop. In Hainan, China, Jatropha is intercropped with peanuts. I have seen the same in West Timor. In Ethiopia, Jatropha is intercropped with tomatoes, coffee, millet, sesame, and so on.

• Intercropping also uses the practice of sowing a fast-growing crop with a slow — growing crop, so that the fast-growing crop is harvested before the slow — growing crop starts to mature. This obviously involves some temporal separa­tion of the two crops.

• Further temporal separation is found in relay cropping, where the second crop is sown during the growth, often near the onset of reproductive development or fruiting, of the first crop, so that the first crop is harvested to make room for the full development of the second.

• Another technique is double cropping or alternate cropping. Biofuel grains like Crambe and Camelina are sown after a wheat or soybean crop on agricultural land, and can be harvested after 4 months. Then farmers sow in wheat or soybeans again on the same piece of land, and harvest these grains before the biofuel cycle starts again.

Investors in energy plantations should follow the “Food First, Fuel Later” prin­ciple, which means that food production must always be given first priority. When cultivating crops like non-edible Jatropha, one should simultaneously invest in food production to assure that local farmers and local communities are positively affected by our presence in the area.

As an example, Biofuel Africa, a Ghanaian corporation wholly owned by Nor­way-based Solar Harvest (www. biofuel. no), claims to have increased the acreage of land available for food production in Northern Ghana by 880%. In 2008, 55 acres of the company’s land was planted with food crops grown by 25 local farmers. Tests showed that repeated growing of food crops had depleted this soil of much of its nutritional content. Biofuel Africa transferred the depleted soil over to Jatropha production, offering the farmers instead the chance to relocate to land leased by Biofuel Africa that had not been previously farmed. Biofuel Africa then cleared and ploughed the land for the farmers, and the farmers themselves planted local staples such as cassava, yam, corn, rice, beans, and peanuts. Within a year, this had been increased from 55 to 540 acres, all of which was leased cleared and ploughed by Biofuel Africa.

Many non-governmental organizations (NGOs) like Friends of the Earth are engaged in the “fuel-or-food” debate and criticize Jatropha. They state that Jatropha is planted on agricultural land and pushes food crops out. With double cropping

and intercropping techniques this “fuel-or-food” debate becomes invalid. Double

cropping even fertilizes the soil!

Advantages of Jatropha intercropping include:

• Jatropha is a slow-growing crop and many Jatropha entrepreneurs or farmers do not have the financial means to wait 5 years before the big crop of Jatropha seeds comes in and provides a return on the investment. A fast-growing crop planted between Jatropha can help to raise extra income.

• Monocropping deteriorates the fertility of the soil. With intercropping, more agricultural land is created and more fertile land can be used for all kinds of agricultural produce.

• The farmers are happy when they learn this technique. They can feed their families better with a bigger variety of food.

5.2