Key Technical Points for Soil Management in Schisandra (Five-Flavor Berry) Orchards
In nature, soil is the foundation for plant growth and fruiting, and the source of water and nutrient supply. When the soil is deep, loose in texture, and well aerated, soil microorganisms are active and can improve soil fertility, which in turn favors root growth and enhances metabolism, and plays an important role in strengthening tree vigor and increasing yield per unit area and fruit quality. Therefore, in pollution-free standardized cultivation of Schisandra, soil management is an important component. Soil management of Schisandra means correctly carrying out fertilization, irrigation, and inter-row management according to its growth and development characteristics and nutritional status, thereby ensuring high, stable yields and high quality and efficiency.
1. Main nutrients required by Schisandra and changes in their seasonal levels
(1) Nitrogen When nitrogen supply is insufficient, Schisandra new shoot growth is weak, leaves are small and pale, vegetative growth ends prematurely, fruit clusters and berries are both smaller, and yield declines markedly. When nitrogen is excessive, branches and leaves grow excessively but are not solid, and the plant is susceptible to disease attack. In a year, nitrogen uptake by Schisandra begins roughly at the same time as budbreak, and the demand for nitrogen is greatest from leaf expansion to before flowering. Therefore, nitrogen fertilizer application should focus on the early growth stage, so that the plant can form robust new shoots and well-developed flowers in the early growth stage, laying a good foundation for fruit set and fruit growth.
(2) Phosphorus Schisandra absorbs phosphorus from the start of new shoot growth in early spring through berry ripening, with the greatest uptake during the period of vigorous new shoot growth and berry enlargement. During berry ripening, phosphorus in stems and leaves is transferred in large amounts to the fruit.
After phosphate fertilizer is applied to the soil, it is quickly fixed, moves very slowly in the soil, and is not easily lost, so phosphate fertilizer can be applied together with base fertilizer. To improve fertilizer efficiency, it should be applied appropriately deep and close to the root system. If phosphorus needs to be supplemented during the growing season, 0.3%-0.4% monopotassium phosphate can be used for foliar spraying.
(3) Potassium Schisandra absorbs potassium throughout the growing season, but as the berries enlarge, potassium uptake increases markedly.
Potassium fertilizer is not easily fixed by the soil after application, so it should be applied appropriately deep and close to the root system, with two topdressings per year, the first in early May (budbreak stage), and the second in the middle growth stage of the plant (early July). Apply 10-25 grams of potassium sulfate per plant per year. During the critical period of flower sex differentiation (late June to early July), 0.3%-0.4% monopotassium phosphate can also be used for foliar topdressing.
(4) Calcium Calcium is an element with relatively high content in the Schisandra plant body, mainly in old leaves, and its content in branches and leaves shows an increasing trend throughout the year (mainly from late May to October). Calcium can transform nitrate nitrogen, so when calcium is deficient, nitrogen deficiency is often likely to occur. When calcium is adequate, fruit quality can be improved.
(5) Magnesium Magnesium is the main element constituting chlorophyll. In Schisandra leaves, its content also changes with the seasons, showing an increasing trend from late May to October, especially with higher content in October. This is particularly obvious from leaf color: the leaves are dark green and glossy, which helps the plant carry out photosynthesis and accumulate nutrients.
(6) Zinc Zinc is related to oxidation-reduction processes and is an important element in plant respiration, and it has the effect of increasing fruit set rate and yield. When zinc is deficient, spots or yellowing appear on the leaves.
(7) Manganese Manganese is related to oxidation-reduction processes in the plant body and has an important effect on chlorophyll formation. Manganese can promote the formation and transfer of sugars, enhance respiration and photosynthesis, and also favor root formation. When manganese is adequate, it can promote growth and fruiting and help increase yield.
The fertilizer efficiency and effects of different fertilizers and fertilization principles are shown in the appendix.
2. Fertilization
(1) Autumn fertilization Apply 3-5 cubic meters of farmyard manure per mu. Starting from a one-year-old orchard, carry out every other year at 0.5 m from the plants on both sides of the trellis surface, and thereafter dig trenches outward in turn along the outer edge of the previous fertilization, applying fertilizer in rotation. The trench is 0.4 m wide and 0.3-0.4 m deep. After fertilization, fill with soil and level it, until farmyard manure has been applied throughout the entire orchard.
(2) Topdressing Topdress twice each year: the first time at budbreak (early May), applying quick-acting nitrogen fertilizer and potassium fertilizer; the second time at the middle growth stage of the plant (early August), applying quick-acting phosphorus and potassium fertilizers. As the tree body expands, fertilizer dosage increases year by year: ammonium nitrate 25-100 grams per plant, superphosphate 200-400 grams per plant, and potassium sulfate 10-25 grams per plant.
(3) Foliar fertilization Schisandra has a relatively poorly developed root system, and berry enlargement, new shoot growth, and flower bud differentiation all consume relatively large amounts of nutrients, easily causing nutrient competition. Therefore, timely foliar spraying at key stages of plant growth, such as the berry enlargement stage and the critical period of flower bud differentiation, has positive significance for ensuring normal plant growth and high and stable yields.