Effect of Yeast Extract on Seedling Growth Promotion and Soil Improvement in Afforestation in a Semiarid Chestnut Soil Area

Yeast extract, which is environmentally friendly, nutritious, and convenient to use, has advantages over common plant growth regulators and soil conditioners. It is worth verifying the effect of the application of yeast extract to afforestation in a semiarid chestnut soil area. This study was conducted through a wild field afforestation experiment in Inner Mongolia, northern China. We designed an orthogonal experiment of 25 treatments with 30 repetitions on Pinus sylvestris (Pinus sylvestris var. mongolica Litv.) sand Armeniaca sibirica (Armeniaca sibirica (L.) Lam). Three factors with different levels were considered: application to rhizosphere soil with the amounts of 0 g, 10 g, 20 g, 30 g, and 40 g; foliar spraying with concentrations of 0%, 0.5%, 1%, 1.5%, and 2%; and spraying at three moments. The results showed that yeast extract could enhance the seedlings of Pinus sylvestris and Armeniaca sibirica. When applying 40 g of yeast extract, the survival rates and root parameters were significantly boosted. Foliar spraying plays an important role in promoting the growth of seedlings. It was most effective for the two species to be sprayed with a concentration of 2% after leafing of the seedlings. The data also revealed that the application of yeast extract improved the properties of the rhizosphere soil. The porosities and moisture contents were increased, and the bulk densities were reduced. Forty grams (40 g) was the best amount to apply, especially for the soil at 20-40 cm where the seedling roots are mainly located. The chemical properties were also improved, as there was a significant increase in the conductivities, organic matter, nitrogen, and phosphorus as well as a slight reduction in the calcium carbonate content and pH. Therefore, yeast extract has a beneficial effect on both seedling growth promotion and soil improvement. It is considered to be an environmentally efficient method for afforestation and ecological remediation in semiarid chestnut soil areas.