The phosphorus cost of agricultural intensification in the tropics.

Agricultural intensification in the tropics is one way to meet rising global food demand in coming decades(1,2). Although this strategy can potentially spare land from conversion to agriculture(3), it relies on large material inputs. Here we quantify one such material cost, the phosphorus fertilizer required to intensify global crop production atop phosphorus-fixing soils and achieve yields similar to productive temperate agriculture.

Eco-certification and greening the Brazilian soy and corn supply chains.

Garrett 's recent letter (2013 044055) shows the trade value of Brazil's production of non-genetically modified (GM) crops, and argues that production for this niche market laid the foundation for the expansion of a variety of non-GM and eco-certification systems. We argue that the conditions underlying the development and perpetuation of the non-GM certification systems are transient. The expansion of soy production has dampened the conditions that promoted the dominance of non-GM soy in the region.

Networks Versus Need: Drivers of Urban Out-Migration in the Brazilian Amazon.

As urbanization rates rise globally, it becomes increasingly important to understand the factors associated with urban out-migration. In this paper, we examine the drivers of urban out-migration among young adults in two medium-sized cities in the Brazilian Amazon-Altamira and Santarém-focusing on the roles of social capital, human capital, and socioeconomic deprivation. Using household survey data from 1,293 individuals in the two cities, we employ an event history model to assess factors associated with migration and a binary logit model to understand factors associated with remitting behavior.

Poverty dynamics, ecological endowments, and land use among smallholders in the Brazilian Amazon.

Rural settlement in previously sparsely occupied areas of the Brazilian Amazon has been associated with high levels of forest loss and unclear long-term social outcomes. We focus here on the micro-level processes in one settlement area to answer the question of how settler and farm endowments affect household poverty. We analyze the extent to which poverty is sensitive to changes in natural capital, land use strategies, and biophysical characteristics of properties (particularly soil quality).

Socioeconomic development and agricultural intensification in Mato Grosso.

The Brazilian agro-industrial frontier in Mato Grosso rapidly expanded in total area of mechanized production and in total value of production in the last decade. This article shows the spatial pattern of that expansion from 2000 to 2010, based on novel analyses of satellite imagery. It then explores quantitatively and qualitatively the antecedents and correlates of intensification, the expansion of the area under two crops per year.

Out-migration and land-use change in agricultural frontiers: insights from Altamira settlement project.

One of Daniel Hogan's lasting impacts on international demography community comes through his advocacy for studying bidirectional relationships between environment and demography, particularly migration. We build on his holistic approach to mobility and examine dynamic changes in land use and migration among small farm families in Altamira, Pará, Brazil. We find that prior area in either pasture or perennials promotes out-migration of adult children, but that out-migration is not directly associated with land-use change.

Transferências intergeracionais privadas na Amazônia rural brasileira.

What motivates family members to share resources? Past research argues for, on the one hand, love and altruism, and on the other, the expectation of reciprocity. Drawing on this literature, this paper examines intergenerational transfers between small farmers and their non-coresident children in the rural area around the city of Altamira, Pará, Brazil. We apply GoM (Grade of Membership) models to create profiles of private transfers, using data collected in 2005 by a team from Indiana University.

Case studies, cross-site comparisons, and the challenge of generalization: comparing agent-based models of land-use change in frontier regions.

Cross-site comparisons of case studies have been identified as an important priority by the land-use science community. From an empirical perspective, such comparisons potentially allow generalizations that may contribute to production of global-scale land-use and land-cover change projections. From a theoretical perspective, such comparisons can inform development of a theory of land-use science by identifying potential hypotheses and supporting or refuting evidence.

Collecting Sketch Maps to Understand Property Land Use and Land Cover in Large Surveys.

This article describes a method to collect data on the spatial organization of land use within a rural property as part of a large-scale project examining the linkages between household demographic change and land use and land cover change in the Brazilian Amazon. Previous studies used several different spatial approaches, including maps and satellite images, to improve the information collected in standard survey questionnaires. However, few used sketch maps to obtain information from the point of view of the survey respondent about the spatial organization of land use and infrastructure.

Confidentiality and spatially explicit data: concerns and challenges.

Recent theoretical, methodological, and technological advances in the spatial sciences create an opportunity for social scientists to address questions about the reciprocal relationship between context (spatial organization, environment, etc.) and individual behavior. This emerging research community has yet to adequately address the new threats to the confidentiality of respondent data in spatially explicit social survey or census data files, however.

Altruistic and contractual remittances between male and female migrants and households in rural Thailand.

Past research has questioned the extent to which remittances are altruistic behaviors versus payments in a contractual relationship between households and migrants. This article explores altruistic and contractual patterns of remittances using a gendered approach. On the basis of results with various levels of significance in regression models, male and female migrants from Nang Rong, Thailand, behave both altruistically and contractually.