[Effects of Balanced Fertilization and Straw Mulching on Soil Nutrients and Stoichiometry in Purple Soil Slope]

To explore the effects of long-term balanced fertilization and straw mulching on soil nutrients and stoichiometric ratios in purple soil sloping cropland, nine plots (length 7 m×width 3 m) were established in Dianjiang County as the research sample area of long-term farmland nitrogen and phosphorus loss monitoring. The following three treatments were set up:conventional mode (CK), balanced fertilization mode (M1), and balanced fertilization+straw mulching mode (M2), with three replications for each treatment to compare the contents of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) and their stoichiometric changes under different treatments from 2018 to 2020. The results showed:K contents showed significant differences among the three treatments in 2018, in the order of CK>M2>M1. NO3--N and NH4+-N contents showed significant differences among the three treatments in 2019, both in the order of M1>M2>CK. Other nutrient contents showed no significant difference among different treatments each year. Soil C and N contents showed non-significant differences among different years. The total K contents of CK, M1, and M2 in 2018 were significantly higher than that in other years and were 78.26% and 98.79%, 19.13% and 35.4%, and 54.49% and 41.76% higher than that in 2019 and 2020, respectively. The total P content in the CK and M2 treatments decreased with years, and that of CK and M2 in 2018 was 20.29% and 10.67% and 39.68% and 17.33% higher than that in 2019 and 2020, respectively. The available potassium (AK) content of the three treatments showed non-significant differences among different years, whereas the contents of nitrate nitrogen (NO3--N), ammonium nitrogen (NH4+-N), and available phosphorus (AP) showed significant differences among the different treatments, with all being the highest in 2020. Soil C:P, C:K, N:P, N:K, and P:K ratios of each treatment showed significant differences among different years (P<0.05). Soil C:K, N:K, and AN:AP ratios all showed significant differences among different fertilization modes in 2018 and 2019, respectively (P<0.05). There was a significantly linearly positive relationship between soil C and N concentration and soil P and K concentration. There were very significant linear positive correlations between soil C:K and C:P, N:K, N:P, and P:K; N:K with C:P, P:K, and N:P; and N:P with C:P, N:P, and C:P. Soil P concentration was highly significantly linearly negatively correlated with C:K and N:K ratios. There were significant positive correlations between soil NO3--N, NH4+-N, AN:AP, and AN:AK; NH4+-N, AN:AP, and AN:AK; and AN:AP and AN:AK. The results suggested that balanced fertilization and straw mulching was a more suitable management mode for purple soil sloping cropland.

[Effect of combined application of inorganic and organic fertilizers on growth and quality of Salvia miltiorrhiza]

The study is aimed through field experiments to study the effect of combined application of organic and chemical fertilizers on the growth and quality of Salvia miltiorrhiza, provide ideas for reducing fertilization while increasing the efficiency as well as improving the quality of produces. The experiment included 6 treatments viz., no fertilization(CK), full application of chemical fertilizer(F), 25% orga-nic fertilizer with 75% chemical fertilizer(M25), 50% organic fertilizer with 50% chemical fertilizer(M50), 75% organic fertilizer with 25% chemical fertilizer(M75), and fully apply organic fertilizer(M100). The results showed that:(1)from the perspective of yield and economic benefits, M75 was the best and M100 second;(2)for effective components, the combined application of organic and chemical fertilizers increased the content of main water-soluble components and the total content of effective components, among which M25 and M50 were better.