LAUSR

The main aim of this study was to evaluate the effects of the maize-cover crop rotation ( Zm - cc ) in the soil net nitrogen mineralisation (NNM) by measuring in situ NNM incubation in the upper soil (0–25 cm) during spring-summer (October–March) and autumn-winter (April–September) seasons and compared with other rotation in Mediterranean Central Chile. The study was carried out at 5 experimental fields (only irrigated in spring-summer period), where four common soil use or maize-based rotations were evaluated: permanent fallow ( F - F ); maize-fallow ( Zm - F ); maize-cover crop ( Zm - cc ); and permanent cover crops ( cc - cc ). In these fields were carried out NNM in situ determinations in F - F ( n  = 18), Zm - F ( n  = 31), Zm - cc ( n  = 43), and cc - cc ( n  = 51) combinations (totalise n  = 143), which were collected during spring-summer and autumn-winter in different periods between 2011 and 2018. During the spring-summer period, it was found that the NNM was highest in the Zm - cc rotations with a mean value of 36 kg N ha −1 , whereas the lowest NNM values were in F - F soil use with and mean of 6 kg N ha −1 . In contrast, during autumn-winter season, the NNM was highest in the F - F soil use with a mean of 34 kg N ha −1 , while the lowest NNM values were found in Zm - cc rotation with a mean of − 38 kg N ha −1 . During the spring-summer period, the Zm - cc rotation had the highest NNM values because cc increased the soil organic matter (SOM) content for microbial activity, whereas in autumn-winter, the Zm - cc rotation had the lowest NNM values because the cc added fresh SOM that increased N immobilisation process.