IMPACTS OF AW ON THE SOIL-PLANT SYSTEM

Agricultural waste has much importance in the current deteriorating environmental scenario where air, soil, and plant health affect the yield losses and the environmental consequences (Table 2.1). The application of agriculture waste in soil has many forms. A study was conducted to check AW’s suitability in soil and biochar obtained from the diy method. Results revealed that slow pyrolysis in AW lowers the alkali and alkaline earth metal along with heavy metals load from soil. It is also economically cheaper than biochar produced by diy method (Kambo and Dutta, 2015). Compost enhances the microbial activity in soil due to which enzymatic activity gets improved. These AW are also involved in the improvement of carbon sequestration in the soils (Oo et al., 2018). Soil physiochemical properties are also enhanced which yields better productivity and yield of crop along with nutritional value improvement (Abujabhah et al., 2016). Fanners have been using organic amendments since long time ago to improve the organic matter content in soil to maintain the healthy fertility status of soil (Scotti et al., 2015). Application of AW in soil significantly improves the soil organic matter and reduces the need of nitrogen and phosphoms application to the soil without affecting the yield (Melo et al., 2018). Coconut husk, woodchips, and orange bagasse have been evaluated and found that orange bagasse biochar enhances nitrogen and phosphoms nutrition. There are numerous positive and negative impacts of AWs on different environs; some are depicted in Figure 2.4.

Along with positive effects some constraints are also there, for example, manure application to soil reduces the activity of Mycorrhizal fungi and reduces their root growth (Elzobair et al., 2016). The addition of compost also has some negative effects on plants. Compost addition to soil increases the organic pollutants in soil and enhances the soil electrical conductivity. It also has issue of some heavy metal contamination in soil and hinders the growth of the seed (Gallardo-Lara and Nogales, 1987).

To avoid environmental issues, AW now a day is applied to soil to better plant production. Composts, biochars, and different manure are applied to achieve the ultimate benefit of getting better crop yield (Elzobair et al., 2016). These AW when processed form, are called organic amendments. These amendments supply the nutrients to plants and help them to grow well. These AW derived amendments give the plants micro and macronutrients to support biological and grain yield. These amendments also improve plants’ chlorophyll contents, improve water uptake, nutrients status, transpiration rates, and reduce heavy metals uptake in plants (Alvarez-Lopez et al., 2016).

On the other hand, there are some disadvantages that exist when we apply AW on plants in different forms. However, there are not many. The disadvantages of using AW include increased soil pH and calcium/magnesium equilibrium disturbance in the soil also disturbs the plant growth (Una et al., 2019), increased pest attacks, decreases fungal growth, AW release nutrients veiy slow' and their continuous application may results in the heavy metals buildup in the soil as these amendments and wastes hinder the heavy metals uptake to plant and adsorb them on their surfaces (Aylaj et al., 2018).