|Amazonia: Resiliency and Dynamism of the Land and Its People (UNU, 1995, 253 pages)|
|6. Agro-forestry and perennial cropping systems|
Four main crops have served as "launching pads" for agro-forestry in the Brazilian Amazon: black pepper, cacao, coffee (especially robusta coffee), and manioc, (appendix 2). Interestingly, two of these mainstays of polycultural systems are exotics: coffee and black pepper. Each of the four main cash crops has served as a springboard for diversifying farming operations for different reasons - black pepper after disease took a serious toll, cacao and coffee because of a sharp drop in prices in the late 1980s, and manioc, because it has traditionally served as the last crop in swidden fields before the plot is abandoned to second growth.
Instead of allowing a field to go fallow, some farmers are prolonging its useful life by opting for agro-forestry. A similar trend is noted on Borneo where some small farmers are planting perennials, such as rubber and durian, instead of allowing swidden fields to go fallow (Brookfield, Potter, and Byron 1995). In the sample of 121 polycultural fields, manioc, was present in 25, and the hardy tuber cultigen was the fourth most common crop in sampled polycultural fields (appendix 5). The tendency to interplant longer-lived perennials with manioc, is particularly noticeable in the Santarém area (appendix 2).
Farmers know that black pepper will eventually fall victim to Fusarium wilt so they often interplant other perennials, such as passionfruit or oil-palm, so that the land still produces income as the black pepper is phased out. As Fusarium symptoms become progressively worse, farmers gradually replace black pepper with other perennials, such as African oil-palm, passionfruit, Barbados cherry, or cupuaçu Even so, black pepper is still the main "money earner" for many farmers engaged in market-oriented agro-forestry systems in the Brazilian Amazon; the labour-intensive crop is the third most common component in the sample of 121 polycultural fields (appendix 5).
In this manner, farmers incorporate diversity into their cropping systems over time. Black pepper paves the way for other crops because fertilizers enrich the soil and rice husks, often placed around the base of black pepper plants, help build up organic matter.
Some of the intercropped perennials are productive for only a few years, so the composition of agro-forestry systems is highly dynamic. Passionfruit, for example, normally produces for only three to five years. Longer-lived perennials are often intercropped as the passionfruit vines mature; one farmer in Tomé-Açu, for example, has intercropped his passionfruit field with various timber trees. A farmer near Capitão Poço has intercropped his passionfruit with longer-lived sweet orange and annatto (Bixa orellana) trees (fig. 6.1). At Sitio Andiroba, near Castanhal, a 25 ha field formerly planted to passionfruit and papaya was replanted with sweet orange after the productivity of the former intercrops declined. With periodic doses of NPK fertilizer, the 5,000 trees in the 25 ha orchard produce about 2.7 kg of oranges per tree every year.