Common bean yield responses to nitrogen fertilization in Brazilian no-till soils: A meta-analysis

ABSTRACT

Although numerous studies have been conducted with common bean regarding nitrogen (N) dose, time of application, and source in no-till (NT) soils in Brazil, the heterogeneity of the results makes it difficult to establish technical recommendations based on individualized studies. This meta-analysis aimed to rank the main factors influencing common bean response to N management in NT areas. The database consisted of 99 scientific papers that encompassed 160 trials and 2394 observations. In general, the probability of obtaining a positive response to N application in common bean productivity was 77 %, with an average 18 % increment (358 kg ha^-1). The main factors that affect the response of common bean grain yield to N fertilization and the choice of the applied N dose are soil organic matter (OM) content and the preceding crop. In soils with OM content >20 g kg^-1, the N dose that determines the highest economic return is 50 kg ha^-1. For soils with OM content <20 g kg^-1, the N dose to be applied is 70 and 100 kg ha^-1 for crops preceded by legumes and grasses, respectively. The timing of the N application did not result in a significant difference in common bean yield in 62 % of the trials. However, the results showed that the average yield increase in the common bean went from 15 % (293 kg ha^-1) with a single application to 32 % (622 kg ha^-1) with split N applications. All N sources tested showed similar gains to those obtained with N application through urea. Excluding situations with high doses of N application (>100 kg ha^-1), inoculating common bean seeds increased grain yields by 6 % on average (118 kg ha^-1). The combined analysis of the available results demonstrated that the crop recommendations used in Brazilian soils under NT could be refined considering the soil OM concentration and preceding crop. Additionally, seed inoculation and N dose splitting in the form of common urea should be recommended.

Phaseolus vulgaris L.; N source; seed inoculation; N application time; N dose