During the second half of the 20th century, the introduction of new chemical agriculture technologies brought about a revolution in food production, but this has also cause deep deterioration in our relationships with the natural environment. In developing tropical countries, record yields were accompanied by rural exodus, widespread deforestation and loss of topsoil. The stonemeal research described herein is an alternative to such practices as it is an environmental friendly and socially responsible technology based on soil rejuvenation and conservation by means of the addition of natural rock powders that are rich in phosphorous, calcium, magnesium, potassium and micronutrients. The research adopted an inter-disciplinary approach and was conducted among small farmers of a rural community located in the state of Minas Gerais, Brazil. The major goal was to demonstrate that there is a harmless cheap and simple alternative to fertilizing degraded or impoverished soils, which allow farmers to sustain high productivity and to remain on their plots of land. Results have confirmed the economic, environmental and productive feasibility and advantage of the stonemeal technique for corn, rise, manioc, sugar cane and horticultural species, when compared to the use of chemical fertilizers. The fertilization of the soil with rocks, allows the understanding of the natural processes, which maintain production levels while building a sustainable fertile soil.

The use of rock powders is an agricultural practice that facilitates the agroecological transition and autonomy of many farmers. These inputs should be used in conjunction with management systems that enhance the weathering of the minerals contained in the rocks. This study aimed to assess the impact of incorporating gneiss powder on soil quality and coffee cultivation within agroecological and organic frameworks, encompassing agroforestry systems (AFSs) as well as areas fully exposed to sunlight (FS). Comprehensive analyses, including chemical, microbiological, and physical assessments, were carried out on the soil. The study involved evaluating various parameters such as electrical conductivity, grain density, total titratable acidity, and pH of the exudates to gauge the coffee quality. Following a 24-month application of rock powder, noteworthy observations included increased soil moisture in agroforestry systems (AFSs), presumably attributable to enhanced nutrient availability (potassium, calcium, magnesium, copper, and zinc) derived from the gneiss powder. In addition, a higher level of CO₂ was derived from microbial respiration than from soil production. Similarly, coffee beans presented lower electrical conductivity, higher density, and fewer defects in AFSs than fully exposed sun systems (FS). The total titratable acidity values remain consistent with the limits indicated in the literature for quality coffees; the pH values, however, were lower. The results suggest that the use of gneiss powder enhances soil microorganism activity and accelerates the biological weathering of minerals for coffee plantations in AFSs.

This study suggests the employment of accumulated sediments in the reservoir of Tucuruí (Pará /Brazil) to remineralize the surrounding degraded soils. The approach was based on the principles of stonemeal technology. It suggests that the soil can be rejuvenated by crushed rocks rich in macro and micronutrients. Removal of the sediments for agricultural use will bring benefits to family farmers and increase the life cycle of the reservoir and, therefore, energy generation. Geochemical data on retained sediments, soils and rocks in the area of influence of the reservoir were evaluated regarding nutrient transport mechanisms and soil-fertility potential. Results show that sediments from the reservoir contain nutrients levels at least one order of magnitude greater than average Amazon region soils. Our data on soil use and occupation in the region show the degradation areas which could be recovered by stonemeal techniques. Thence, an Agroforestry System was installed, with 12 plots where different mixtures of sediments removed from the reservoir were used, along with crushed rock with or without the addition of NPK and manure. The experiments showed that maximum crop yield and plant growth were attained in the plots where a mixture of sediments, crushed rocks and manure were added.