The study looked at how different types of fertilizers affect soil productivity for growing wheat and maize in North China. They tested seven types of fertilizers on a field for 18 years and found that organic fertilizer was the most effective. Fertilized soil produced more wheat and absorbed more nutrients than unfertilized soil. The best fertilizer combination was a mix of organic and chemical fertilizers. Using balanced NPK fertilizer led to higher wheat yields compared to unfertilized soil. The study showed that soil organic matter is crucial for soil productivity and nutrient uptake in crops.