A healthy soil acts as a dynamic living system that delivers multiple ecosystem services, such as sustaining water quality and plant productivity, controlling soil nutrient recycling decomposition, and removing greenhouse gases from the atmosphere. Soil health is closely associated with sustainable agriculture, because soil microorganism diversity and activity are the main components of soil health. Agricultural sustainability is defined as the ability of a crop production system to continuously produce food without environmental degradation. Arbuscular mycorrhizal fungi (AMF), cyanobacteria, and beneficial nematodes enhance water use efficiency and nutrient availability to plants, phytohormones production, soil nutrient cycling, and plant resistance to environmental stresses. Farming practices have shown that organic farming and tillage improve soil health by increasing the abundance, diversity, and activity of microorganisms. Conservation tillage can potentially increase grower’s profitability by reducing inputs and labor costs as compared to conventional tillage while organic farming might add extra management costs due to high labor demands for weeding and pest control, and for fertilizer inputs (particularly N-based), which typically have less consistent uniformity and stability than synthetic fertilizers. This review will discuss the external factors controlling the abundance of rhizosphere microbiota and the impact of crop management practices on soil health and their role in sustainable crop production.

Interactive effects of increased phosphorus (P) with salinity were studied at the microculture level of African violet (Saintpaulia ionantha). Increased P from 0.5 to 2.0 mM in the medium was very effective to mitigate the adverse effects of increased NaCl salinity (0.0, 50, 75, 100 mM). Growth (shoot height, and dry mass) was significantly reduced with increased salinity, whereas increasing P improved growth with elevated salt concentrations. Leaf osmolarity was decreased (more negative) with salinity effect and it was increased (less negative) by P treatments. Percent ash was increased with salinity and it was not highly affected by P. Root number and root length were significantly reduced with increased salinity and improved with increased P. The percentage of shoot content of nitrogen (N), P, calcium (Ca), potassium (K), and mag-429 ORDER REPRINTS nesium (Mg) were reduced with elevated salinity level and this reduction was less as P concentration increased in the medium. Sodium (Na) was significantly increased with imposed salinity and its uptake was reduced with increased P level. Zinc (Zn), manganese (Mn), and copper (Cu) uptake were increased with elevated salinity level and reduced with elevated P level in the media. Increased NaCl level strongly reduced Fe uptake and P was very effective in increasing iron (Fe) uptake. An overall increased P was very effective in regulating macro and micronutrients uptake, counteracting the increased salinity adverse effects. We can conclude that P is a key element for studying the physiological responses of different plant species to salinity. Also in vitro cultures (a rigorously controlled system) could work as an efficient alternative for the study of salinity.

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