Why might fewer deficiencies appear on farms that utilize manure or biosolid applications?

Fewer deficiencies might appear on farms that utilize manure or biosolid applications primarily due to the increased nutrient supply from organic matter. Manure and biosolids are rich in essential nutrients such as nitrogen, phosphorus, and potassium, as well as micronutrients that are vital for plant growth. When these organic materials are applied to the fields, they not only provide immediate nutrients but also improve soil health and fertility over time.

Organic matter enhances the soil's structure, leading to better water retention and aeration, which in turn supports healthy root development and nutrient uptake by plants. Additionally, the slow release of nutrients from organic amendments like manure means that plants have a more sustained supply of nutrients throughout their growth cycles, reducing the likelihood of deficiencies.

In contrast, the other options do not directly address the nutrient supply aspect. Higher costs of fertilizers (the first option) might lead farmers to use fewer chemical inputs, but this does not inherently solve nutrient deficiencies. Better pest control measures (the second option) and the use of only chemical fertilizers (the last option) may contribute to better overall crop management but lack the specific capacity to address nutrient deficiencies as effectively as the organic contributions from manure and biosolids can.