**6. Oilseed yield and quality as influenced by soil amendments**

Oilseed crop yield and oil quality is influenced by both biotic and abiotic factors. Oil quality is governed by three major compounds namely, fatty acids, triglycerol and bioactive compounds which depend upon crop variety, weather conditions and post-harvest methods [72]. Soil health deterioration with less to no use of organic manures, chemical fertilizers, intensive cultivation, sulfur free fertilizers etc. are major constrains in enhancing oilseed productivity. Sulfur is an essential macronutrient that play important role in protein synthesis, regulates N assimilation inn crops, coenzyme-A, biotin, vitamins etc. and determines oil quality. Oilseed crops are heavy S feeder crops and can remove 10 to 25 kg per year depending upon soil, crop and environmental conditions [73]. Incorporation of soil amendments with recommended fertilizer doses to oilseed crops will have beneficial effect on improving soil physic-chemical and biological properties, improving soil health directly influencing productivity and oil quality (**Figure 3**). Potential yield gap can be minimized by best soil management practices to enhance nutrient availability and uptake by crops. Integrated nutrient management of incorporating fertilizers and organic resources are effective strategy to enhance oilseed productivity. Organic amendments such as compost, green manures etc. acts as slow release organic fertilizers to meet crop demand. Thus, enhancing nutrient uptake by decreasing loss via leaching, runoff, volatilization and increasing nutrient use efficiency.

Soil amendment as nutrient source and soil conditioner can alleviate salinity problems, micro and macro nutrient stress, enrich biodiversity thereby enhancing nutrient supplying capacity of soil. Positive effect of soil amendments such as organic manures, zeolites etc. improved crop yield under water deficit conditions in soybean [74] and sunflower [46]. Soil amendments such as organic manures enhances rain

#### **Figure 3.**

*Soil dynamics and crop performances influenced by soil amendments.*

water use efficiency of oilseed crops. According to Adeli et al. [75] organic amendments could increase crop yield by 42% over only mineral fertilizer application. However, crop yield response varies depending upon crop species, soil amendments, edaphic factors and climatic parameters. Ulzen [56] reported that soils treated with rhizobia, P fertilizer and fertisol (manure) showed higher water retention in soil and improved water use efficiency for increasing soybean yield. Organic amendments supply micronutrients, stimulate soil microbial activity and continuously provide nutrients to improve crop yields. Thus substituting chemical fertilizers with organic amendments can be economically feasible and environment friendly approach for sustainable production. Substituting nearly 25–50% of synthetic fertilizers with organic manures/ compost provide better crop yield response and enhance fertilizer use efficiency in oilseed crops. This is due to modification in soil properties such as soil pH, soil fertility, resilience of soil aggregates, soil microbial biomass which enhances ecosystem services and functions, influencing carbon and nitrogen use efficiency. Thus combined application of different types of organic amendments could improve crop yield for long term without deteriorating soil environment. Several studies have shown significant impact of soil amendments on oilseed yield and quality is described in **Table 4**.

Beside the beneficial effect of organic amendments, they also have some detrimental effect on soil ecosystem and human health. The major drawback with application of amendments such as biosolids, sewage sludge, etc. is poor segregation of waste at source that could have hazardous effect on soil environment. Application of immature compost, untreated materials often lead to agronomic and environmental problems. Organic amendments of various types can contain pathogen, pollutants, heavy metals, emerging contaminants such as antibiotic resistance genes, endocrine disruptors, microplastics etc. [33, 92]. Moreover, if unstable organic amendments are applied to land could result in ammonia volatilization, deplete oxygen, release some toxic compounds and immobilize nutrients hindering crop uptake. Indiscriminate and overuse of some amendments might result in environmental pollution by high release of N and P into ground water, rivers etc., eutrophication problems, immobilization of nutrients,


*Soil Amendments: An Ecofriendly Approach for Soil Health Improvement and Sustainable… DOI: http://dx.doi.org/10.5772/intechopen.106606*


#### **Table 4.**

*Oilseed yield response as influenced by soil amendments.*

greenhouse gas emission, acidification, salinization etc. [93]. Therefore, safe handling of soil amendments especially from municipal solid waste, sewage sludge, industrial waste etc. is essential for maintaining environmental and human health.
