**9. Irrigated production**

Cassava benefits from extra irrigation during rainless times when planted near the end of the rainy season or when the rainy season is relatively short. On level or almost flat land, flood or furrow irrigation can be used, but on sloping soil, overhead sprinklers or a spinning water cannon may be more practical. Irrigation at 100% of the crop's water needs increased the root production attained without irrigation. It also marginally enhanced the starch content of roots while significantly lowering the hydrogen cyanide concentration [18].

Drip irrigation, which saves water while keeping soil moisture at a level that is very beneficial to crop growth, is more successful in terms of water use efficiency. Drip irrigation saves water by giving modest and frequent water applications (it also allows the farmer to water the cassava plants but not the weeds). Drip irrigation of cassava generated roughly the same yields as flood irrigation in trials in the severely arid zone. When drip irrigation was employed with the same amount of water as flood irrigation, yields increased significantly, reaching 67.3 tonnes somewhere in India [19]. Experiments conducted in south-western Nigeria yielded similar results. Rainfed cassava yielded root yields of fewer than 5 tonnes per hectare during the growing season. In plots with supplemental drip irrigation, yields increased dramatically as the amount of water provided increased. Irrigation resulted in yields of about 30 tonnes at 100% rainfall.

#### **10. Crop nutrition**

Agriculture must literally return to its roots to attain the increased production required to fulfill present and future demand by recognizing the value of healthy soil, drawing on natural sources of crop nutrition, and properly applying mineral fertilizer. The overuse of mineral fertilizer in agricultural production has resulted in severe environmental consequences, such as soil acidification, water contamination, and air

pollution. Fertilizer use that is more focused and sparing would save farmers money while also ensuring that nutrients reach crops and do not harm the air, soil, or rivers. The environmental impact of mineral fertilizer is a matter of management. In other words, the way with which fertilizers are used, particularly nitrogen (N) and phosphorus (P), affects whether this component of soil fertility management is beneficial to crops or harmful to the environment. Experience shows that crop nutrients from a mix of mineral fertilizer and organic sources, such as animal manure and trees and bushes, enrich the soil with nutrients, resulting in better and more sustainable yields of crops. Other biological relationships, such as those between plant roots and soil mycorrhizae, can improve crop nutrition. The foundation of a sustainable crop nutrition system that yields more is a mix of ecological processes and judicious application of mineral fertilizer [12]. On soils where many other crops would fail, cassava may flourish and generate reasonable yields. It has a great tolerance for low-phosphorus and can often thrive without the use of phosphorus fertilizer. This is because cassava has created a favorable relationship with a fungus group known as "vesicular-arbuscular mycorrhizae" [13]. Mycorrhizae, which may be found in almost all natural soils, penetrate the cassava root and feed on the sugars it produces. In exchange, the fungi's long filaments transfer phosphate and micronutrients to the plant from the surrounding soil. Cassava can absorb enough phosphorus for optimum growth because to this mutual relationship.

The plant tops contain the majority of the nutrients taken by cassava during its growth [6]. After the root harvest, returning stems and leaves to the soil as leaf litter or mulch nourishes the soil with new organic matter, and some of the nutrients are re-used by the following crop. When the plant tops are recycled, the root harvest eliminates less soil nutrients than most other crops [3]. A root yield of 15 tonnes per ha removes only about 30 kg of nitrogen, 20 kg of potassium (K), and just 3.5 kg of phosphorus [20]. Even after many years of continuous cassava production on the same land, there is little risk of phosphorus depletion. Cassava may be cultivated on very acidic and low-fertility soils due to its tolerance for low pH and the large levels of exchangeable aluminum that come with it. While maize and rice yields are typically negatively impacted when the soil pH is below 5 and aluminum saturation is above 50%, cassava yields are typically unaffected until the soil pH is below 4.2 and aluminum saturation is beyond 80%. As a result, cassava may not require a lot of lime on acidic soils where other crops would struggle to do well.
