Jackie Lyn Guevara, & Kevin W. Frank
Abstract
A soil testing philosophy converts soil test concentration from laboratory soil analysis into nutrient recommendations. Recently, a new soil testing philosophy called Minimum Levels for Sustainable Nutrition (MLSN) was developed to provide a more sustainable approach for turfgrass fertilization and being adapted by turfgrass managers. However, there is a lack of peer-reviewed research on this topic. The objective of this research was to compare the effects of MLSN to the traditional philosophy, Sufficiency Level of Available Nutrient (SLAN), on a mix stand of 80% annual bluegrass and 20% ‘Penncross’ creeping bentgrass grown on United States Golf Association specification rootzone. Research was initiated in 2019 at Hancock Turfgrass Research Center, Michigan State University. The whole plot included three levels: MLSN, SLAN and nitrogen (N) fertilized control treatment. The subplot included two levels: trafficked and non-trafficked. Soil samples were collected in spring and autumn to a depth of 15 cm. Turfgrass color, quality, and NDVI were measured monthly. In 2019, nutrient recommendation rate for MLSN was 73 kg N, 37 kg P and 60 kg K ha-1; SLAN was 73 kg N, 147 kg P and 267 kg K ha-1; and N-fertilized control was 73 kg N ha-1. There were no differences among treatments for NDVI, color and quality but the SLAN philosophy had the highest soil P and K levels in autumn of 2019. In 2020, nutrient recommendation rate for MLSN was 73 kg N, 38 kg P and 67 kg K ha-1; SLAN was 73 kg N, 32 kg P and 217 kg K ha-1; and N-fertilized control was 73 kg N ha-1. Both philosophies exhibited higher quality and healthier color compared to N-fertilized control. SLAN philosophy had the highest soil P level but there were no differences in soil K levels between the two philosophies in autumn of 2020.
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