Light soils occupy 8% of the Brazilian territory and are especially expressive in the new and last agricultural frontier in Brazil: the Matopiba region - in the states of Maranhão, Tocantins, Piauí, and Bahia -, where they represent 20% of the area. These soils fit into the textural classes of sand and loamy sand or sandy loam, down to 0.75-m soil depth or deeper, and they are mainly represented by Neossolos Quartzarênicos (Quartzipsamments) and, partly, by Latossolos (Oxisols) and Argissolos (Ultisols). The understanding of soil functioning depends on the establishment of distinguishing criteria for: organic matter dynamics; content and mineralogy of the clay fraction; coarse sand and total sand contents, in relation to those of fine sand; mean diameter of the sand fraction; and water retention capacity. These criteria can contribute for the zoning and for the conservation and fertility management of light soils, as well as for the estimation of their agricultural potential. Integrated production systems, such as crop-livestock and crop-livestock-forestry integration, besides no-tillage with crop rotation, mixed forestry planting with legumes, and the use of green manure and cover crops are relevant for the proper management of these soils. The objective of this review was to characterize light soils and to highlight the main challenges regarding their agricultural potential and their conservation and fertility managements, in face of the expansion and consolidation of the new Brazilian agricultural frontier.

The soil conservation movement in Brazil has been a major driving force in the continuing search for agricultural farming systems that are more sustainable than what we have today, particularly in tropical and subtropical areas. The development and adoption of Zero Tillage Conservation Agriculture (ZT/CA) was the key to the success of this movement, generating agricultural, environmental, and societal benefits.Adoption of the ZT/CA philosophy and technologies is currently practiced on more than 50% of the annual crop area. This is due to the work and innovations of pioneering farmers, agronomists, researchers, and consultants that were and are involved in these efforts. This extensive adoption of ZT/CA occurred after many unsuccessful efforts to mitigate against the devastating effects of soil erosion that were threatening the entire agricultural industry in Brazil. Technicians and farmers realized that erosion control required continual cover of the soil to guard against the torrential rain storms common to these regions. This triggered the efforts of soil conservation pioneers at different points in time and regions of Brazil.In southern Brazil, Herbert Bartz, watched his topsoil eroding away in torrents of runoff. This set him thinking and searching for alternatives, resulting in his adoption of ZT/CA farming in 1972. Ten years later in Brazil's centre-western savannah (Cerrado biome), farmers, researchers, crop consultants and agro-industry initiated efforts to expand cultivation into the very difficult production region of the Cerrados. This was successfully achieved through the pioneering work of agronomist John Landers, bringing experience from the ZT/CA farmer association networks in the south.These were the turning points in the sustainable development of annual crop farming in Brazil. Today, society recognizes the role of these pioneers as key to achieving social, economic and environmental sustainability. ZT/CA reversed the historically accelerating degradation of soil organic matter and soil structure by abandoning conventional tillage, thus improving soil physical and chemical characteristics. This was achieved by promoting cover cropping and permanent soil cover with crop residues, crop rotations, and complementary, environmentally suitable soil management technologies

The origins, history, and recent advances in Conservation Agriculture (CA) are reported. CA is now practiced worldwide on some 200 million hectares, important for mitigating climate change and ensuring food security. Its bedrock is Zero Tillage (ZT) with crop rotation and retention of crop residues. CA approaches Organic Agriculture (OA) when coupled to biological control providing opportunity for OA to become truly sustainable. Ley Farming (LF) and agroforestry with ZT are important for carbon sequestration and land use intensification. Hidden cost: each ton of carbon immobilizes 83 kg of N, 29 kg of P, and 14 kg of S. Industry-backed Regenerative Agriculture (RA) variants have no scientific definition, but generally adopt CA. Sustainable, profitable, and compatible new technologies are emerging and CA needs to embrace them to present a holistic, sustainable package to the farmer. How? A single definition for agricultural sustainability via a multi-stakeholder world congress would standardize certification and de-confuse the market. RA describes exactly what CA does for soil health and all farmers need to unite around a new “Combined Regenerative Agriculture” (CRA) to lobby for adequate payments for environmental services. Expansion of CA is critical for world sustainability. Many gaps and constraints exist, especially for smallholders.