Agricultural Systems Located in the Forest-Savanna Ecotone of the Venezuelan Amazonian. Are Organic Agroforestry Farms Sustainable?

Danilo López-Hernández,Carmen Leonor Hernández,Ana Yamila López-Contreras,Igor Netuzhilin

doi:10.3390/su1020215

Danilo López-Hernández, Carmen Leonor Hernández + Show 2 more

Open Access

https://doi.org/10.3390/su1020215

Copy DOI

Abstract

The savannas located in the forest-savanna ecotone in the Venezuelan Amazon have unfertile sandy ultisols and entisols which show a very low crop production unless they are supplemented with large amounts of fertiliser. In spite of this restriction, local farmers have established long-term production systems by using low input doses of organic manure. The use of organic waste in unfertile ultisols and entisols typical of savannas have resulted in increases in organic matter content and biological activities in soils with respect to inorganic fertilised or non-fertilised natural savanna, which, in turn, may be related to increases in crop productivity. These results could be a successful and reliable soil management technique for rehabilitation of the South American savannas.

Highlights

Neotropical savannas represent, due to their extension, one of the last frontiers for agricultural expansion, the savannas of the Brazilian Cerrado and the Llanos of Venezuela and Colombia have been under intensive agricultural activities after the introduction of commercial crops, improved grasses and agroforestry tree plantations in concerted government programs that started at least forty to fifty years ago [1,2,3,4]
The total organic carbon content (TOC) increased from 6,525 mg kg-1 in the residual cassava amended site (GM) to a highest value (33,050 mg kg-1) in the cow manure site (CM), the farms amended with chicken manure (CHM) and compost (Comp) presented intermediate values
(11,575- 12,530 mg kg-1); the values in the treatments significantly differed from the control only in the cases of cattle manure (CM) and CHM

Summary

Introduction

Neotropical savannas represent, due to their extension, one of the last frontiers for agricultural expansion, the savannas of the Brazilian Cerrado and the Llanos of Venezuela and Colombia have been under intensive agricultural activities after the introduction of commercial crops, improved grasses and agroforestry tree plantations in concerted government programs that started at least forty to fifty years ago [1,2,3,4]. The savannas located at the border of the Amazon forest around Puerto Ayacucho, Amazonas State, Venezuela (Figure 1), have ultisols and entisols developed under strong weathering induced by high temperatures and precipitation in that area. The soils, in the area, have a very high sand content (> 93%), so, besides the low fertility, a poor water holding capacity affects crop production

Methods

Results

Discussion

Conclusion