Influence of Poultry Litter on Crop Productivity under Different Field Conditions: A Meta‐Analysis

CORE IDEAS: Meta‐analysis showed that poultry litter’s influence on crop productivity is comparable to that of inorganic fertilizer.Poultry litter’s effectiveness on crop yield is influenced by soil properties, tillage, application practice, and crop species.More positive effects were found in acidic soil compared with neutral or alkaline, in loam soil compared with sand or clay, under conservation tillage compared with conventional, by subsurface banded poultry litter compared with broadcast or incorporation through tillage.The full benefits of using poultry litter was achieved from long‐term studies, with litter improving crop yield compared with inorganic fertilizer. Research has shown that poultry litter (PL) can be used as a nutrient source for crop production. However, yield responses often varied when compared with inorganic fertilizer (IF) depending on soil type, management conditions, and PL application practices. Therefore, we reviewed the literature and conducted a meta‐analytic assessment to summarize the effects of PL vs. IF on yield response under different agricultural practices. A total of 866 observations from 90 studies were evaluated to determine how soil properties, tillage, application practices, crop species, and repeated applications influenced yield. Poultry litter significantly increased yield in loam, sandy loam, and silty‐clay loam soils, whereas yields were significantly greater with IF in sand and silty‐clay soils; no differences were observed between PL and IF with clay loams or silt loams. Under conventional tillage, IF’s effect on yield was positive, albeit not significant, whereas PL had a significant positive effect under strip‐till or no‐till. Poultry litter produced slightly lower yield when surface incorporated, but higher yield with subsurface band application when compared with IF. Poultry litter had significantly higher yield with cotton (Gossypium hirsutum L.), corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and peanut (Arachis hypogaea L.), significantly lower with bermudagrass [Cynodon dactylon (L.) Pers] than IF, and no effects on tall fescue (Festuca arundinacea Schreb.), corn silage, rice (Oryza sativa L.), and wheat (Triticum aestivum L.). Overall, PL was comparable to IF. However, the greatest benefits of PL on yield when compared to IF tended to occur following repeated (three or more) annual applications.