Explain what will happen if in a cultivated field only manures are supplied and in another field only fertilizers are supplied, keeping all other conditions similar.
Manure are poor in nutrient content than fertilisers; however, they are rich in organic matter. If only manure is added to a field, then the plants of that field will have stunted growth. This is because the field has a low nutrient content. Also, the plants will have nutrient deficiency that arise due to lack of specific nutrients. However, the soil of the field will have a better water-retention capability due to the presence of humus in the soil.
On the other hand, if we add only fertilisers in a field, then the plants of that field will have a better and healthier plants. This is because the fertilisers are very rich in plant nutrients. However, the continuous use of fertilisers may cause disturbance in the aquatic ecosystem due to passage of chemicals from the field to nearby ponds and rivers via rain or irrigation.