A study looked at how using different types of fertilizers affected soil fertility in rice-wheat fields over 11 years. They found that not using any fertilizer led to a decrease in soil organic matter and nitrogen, while using chemical fertilizers increased them. Adding phosphate fertilizer increased soil phosphorus, but potassium levels were low unless straw was returned to the soil. Imbalanced fertilization reduced crop yield and fertilizer efficiency, and caused soil nutrient depletion. Applying 150 kg/ha of nitrogen per season maintained soil nitrogen, but using 60-75 kg/ha of phosphorus led to a surplus. Soil potassium was deficient in all treatments except when straw was returned.