A study was done to figure out the best way to use fertilizers and manure to grow potatoes, onions, and rice in Bihar. They found that potatoes need a lot of nitrogen, phosphorus, and potassium, while onions need less, and rice only needs nitrogen and potassium. Adding manure to potatoes helped a lot, and using it with nitrogen kept crop yields high. Using manure for 5 years made the soil healthier and balanced out the effects of urea. Overall, using manure and nitrogen together gave the best results for growing these crops in Bihar.