Effects of fertilization gradient on the production performance and nutritional quality of cultivated grasslands in karst areas

Abstract

Optimal fertilization is an important measure for managing cultivated grasslands, and a necessary means for maintaining the nutrient balance, yield, and quality of grassland ecosystems. This study aimed to explore the effects of organic fertilizers on the production performance and nutritional quality of cultivated grasslands in karst areas. Two types of monocultured cultivated grasslands (i.e., Medicago sativa and Dactylis glomerata) were employed as the research objects, and a randomized block design was adopted to investigate the effects of five fertilization gradients on the forage height, coverage, yield, and nutritional quality of the cultivated grasslands. According to the results, the plant height, coverage, and yield of M. sativa first presented an increasing trend, then decreased with increasing fertilization gradient, with a peak at 20–30 t/hm2 fertilization gradient. The height, coverage, and yield of D. glomerata increased gradually with increase in fertilization gradient, and peaked at 40 t/hm2. Meanwhile, the crude protein (CP) and ether extract (EE) contents of both grassland types displayed first presented an increasing trend, then decreased with increasing fertilization gradient, and peaked at 10–30 t/hm2 fertilization gradient. The neutral detergent fiber (NDF) and acidic detergent fiber (ADF) contents of M. sativa presented “N-shaped” and “M-shaped” change trends with increasing fertilization gradient, while those of D. glomerata showed “V-shaped” and “M-shaped” change trends, reaching minimum values under fertilization gradients of 30 and 20 t/hm2, respectively. Year, fertilization, and year × fertilization (Y×F) significantly affected the plant heights, coverages, dry/fresh weight ratios, and yields of M. sativa and D. glomerata. The contribution of coverage to the subordinate function of M. sativa was greatest at a fertilization gradient of 20 t/hm2. Meanwhile, the subordinate function values of the height and coverage of D. glomerata increased gradually with increasing fertilization gradient, but the difference in the subordinate function value of height was only 0.09%–0.18% under the fertilization gradient of 20–40 t/hm2. Evaluation of forage nutrition revealed 10–30 t/hm2 and 20–30 t/hm2 as the optimal organic fertilizer application rates for M. sativa and D. glomerata, respectively.

Optimizing nitrogen and phosphorus application to improve soil organic carbon and alfalfa hay yield in alfalfa fields

“…(Wang et al, 2020). Furthermore, high nutrient inputs can impact the production performance of alfalfa (Wang et al, 2023). Therefore, it is necessary to establish appropriate fertilizer application methods to enhance the SOC content and hay yield in alfalfa fields.…”

“…The application of nitrogen also induces alterations in the composition of soil microbial communities, hence facilitating the build up of SOC (Tang et al, 2023). Concurrently, the utilization of nitrogen and phosphorus increased the levels of soil nutrients (with initial soil phosphorus levels of 0.45 g•kg -1 and 0.76 g•kg -1 ), which led to the promotion of alfalfa growth and an increase in photosynthetic rates, consequently leading to elevated inputs of soil carbon (Hakl et al, 2021;Sun et al, 2022;Wang et al, 2023). It has been demonstrated that the application of phosphorus has an impact on the content of SOC, but not alter the geographical distribution of SOC fractions.…”