The Diversity of Bitter Manioc (Manihot Esculenta Crantz) Cultivation in a Whitewater Amazonian Landscape

James A Fraser

doi:10.3390/d2040586

Abstract

While bitter manioc has been one of the most important staple crops in the central Amazon for thousands of years, there have been few studies of its cultivation in the fertile whitewater landscapes of this region. Anthropological research on bitter manioc cultivation in the Amazon has focused almost exclusively on long-fallow shifting cultivation in marginal upland areas of low soil fertility. This has contributed to the persistence of the oversimplified notion that because bitter manioc is well adapted to infertile upland soils; it cannot yield well in alluvial and/or fertile soils. I hypothesized that bitter manioc cultivation would be well adapted to the fertile soils of the whitewater landscapes of the central Amazon because of the centrality of this crop to subsistence in this region. In this article, I examine one such whitewater landscape, the middle Madeira River, Amazonas, Brazil, where smallholders cultivate bitter manioc on fertile Amazonian Dark Earths (ADE) and floodplain soils, and on infertile Oxisols and Ultisols. In this region, cultivation on fertile soils tends to be short-cycled, characterised by short fallowing (0–6 years) and shorter cropping periods (5–12 months) with a predominance of low starch fast maturing “weak” landraces. By contrast, cultivation on infertile soils is normally long-cycled, characterised by longer fallows (>10 years) and longer cropping periods (1–3 years) with a predominance of high starch slow maturing “strong” landraces. This diversity in bitter manioc cultivation systems (landraces, fallow periods, soils) demonstrates that Amazonian farmers have adapted bitter manioc cultivation to the specific characteristics of the landscapes that they inhabit. I conclude that contrary to earlier claims, there are no ecological limitations on growing bitter manioc in fertile soils, and therefore the cultivation of this crop in floodplain and ADE soils would have been possible in the pre-Columbian period.

Highlights

Manioc (Manihot esculenta Crantz) has been the single most important staple carbohydrate energy source to Amazonian peoples for thousands of years [1,2,3,4,5,6]
I conclude that contrary to earlier claims, there are no ecological limitations on growing bitter manioc in fertile soils, and the cultivation of this crop in floodplain and Amazonian Dark Earths (ADE) soils would have been possible in the pre-Columbian period
Bitter manioc cultivation in infertile soils (Oxisols and Ultisols) along the middle Madeira River is characterised by more extensive long-cycled swidden-fallow systems with larger fields, longer fallows and a predominance of what locals refer to as “strong” landraces

Summary

Introduction

Manioc (Manihot esculenta Crantz) has been the single most important staple carbohydrate energy source to Amazonian peoples for thousands of years [1,2,3,4,5,6]. Manioc varieties are classified as either bitter or sweet, depending on cyanogenic glucoside content. Bitter varieties require detoxification for consumption, but yield well in poor, acid soils, have a high starch content, and are more resistant to pests and pathogens. Sweet varieties can be eaten roasted or boiled with no need for detoxification, but they are more vulnerable to attack from pathogens, insects and mammals, yield less starch and require better soils [7,8]. The majority of people living in rural areas of the Brazilian Amazon today are sedentary and culturally inclined to consume manioc in the processed form farinha (toasted flour) which, combined with fish, forms their staple diet [9]. Bitter manioc—the most commonly cultivated of the two—is the staple in many parts of the Amazon basin, along the courses of the major rivers in Eastern, Central and Northwestern Amazonia and in the wider

Objectives

Methods

Conclusion