Influence of poultry litter on nutrient availability and fate in plant-soil systems: A meta-analysis

Interest in using poultry litter (PL) as a nutrient source for crop production has increased in recent years. Utilization of PL can increase soil residual nutrients, thereby potentially increasing soil fertility and crop nutrient uptake. Conversely, PL addition may increase the transport of nutrients to the environment. This study aimed to elucidate the influence of PL on plant nutrient uptake, soil fertility, and environmental issues as compared to commercial fertilizer (CF) using a meta-analytic assessment. The synthesis was based on 134 studies (3,362 comparisons). Positive effects on soil fertility were observed, with PL significantly increasing cation exchange capacity (CEC), pH and soil carbon (C), total nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), and zinc (Zn) concentrations compared to CF. Effects of PL on plant macro- and micronutrients varied depending on the plant tissue parts evaluated when compared to CF, with the leaves and stems generally having lower nutrient concentrations than the reproductive parts. Poultry litter influenced plant nutrient uptake, with a slightly negative effect being observed for N but significant positive effects for P and K. In addition, our results showed that litter application significantly increased carbon dioxide (CO₂) and nitrous oxide (N₂O) fluxes, but decreased nitric oxide (NO) emission. Subsurface-banding application of PL significantly decreased N and P loss in runoff. Overall, this meta-analysis validates the positive effects of PL on plant nutrient uptake and soil fertility and demonstrates that PL can be an effective alternative nutrient source to CF for crop production.