Rice is a plant that needs silicon (Si) as a nutrient to grow well. Silicon is an element of silica (SiO2) found commonly in sand. Rice yields decrease when soils are depleted in available silicon. A possible solution is to add silicon-rich manure to soils. Song et al performed a 10-year field experiment and found that adding silicon-rich manure doubled the amount of available silicon in soils. Using manure brings the additional benefit of recycling organic waste and providing other plant nutrients such as nitrogen and phosphorus
Intensive soil fertilization with mineral fertilizers has led to several issues such as high cost, nitrate pollution, and loss of soil carbon. Fertilization with organic wastes such as anaerobic digestates is an alternative for sustainable agriculture. Conflicting results in the literature have questioned the effectiveness of anaerobic digestates as organic fertilizers. The review by Roger Nkoa demonstrates the fertilizer values of anaerobic digestates. However, anaerobic digestates emit amonia (NH3) and contain copper (Cu), Zinc (Zn) and manganese (Mn) that could pollute the soil and the atmosphere upon repeated soil applications.
Climate change and most actual world food issues are linked directly or indirectly to soil loss of carbon and fertility. Here composting appears as a cheap and sustainable solution.The review by Martínez-Blanco et al. presents nine benefits of compost application to the soil. Composting practices are classified into short-term, mid-term, and long-term benefits.