Methods and Technical Key Points for Trunk-Cutting Planting of Black Locust in Autumn and Winter

Late autumn and early winter is the best time for trunk-cutting planting of black locust. Its characteristics are as follows: First, it avoids the spring tree-planting peak period and the busy farming season, makes full use of the winter slack period, and fully guarantees the timing and quality of planting. Second, according to the physiological characteristics of black locust, the daily average temperature required for root growth is relatively low; after leaf fall in autumn the aboveground part stops growing while the underground part still grows for a period, and when the leaves fall the mobile nutrients in the branches and leaves return to the trunk and roots, so the roots are rich in stored nutrients at that time, which exactly gives the root system a growth stage. Third, the plots for planting black locust are generally rather dry, and late autumn and early winter come right after the rainy season, when the soil moisture is better than in spring, so planting at that time is more conducive to root growth and thus improves the survival rate of planting. For newly planted black locust seedlings, before the severe winter arrives the root system has already recovered and grown for a period; the following spring the seedling revival period is short, and once the temperature is suitable the root system grows immediately, then sprouts from the root crown to form new branches.

I. Planting time: plant as soon as possible after all the leaves have fallen each November.

II. Seedling size: for afforestation on barren hills, generally select seedlings with a ground diameter of more than 0.7 cm; for roadside greening, large seedlings with a ground diameter of more than 2 cm may be selected. A complete root system must be retained, with a root length of not less than 25 cm and a root spread of not less than 20 cm.

III. Planting technique: autumn and winter planting generally adopts the method of planting immediately after digging. When digging the hole, place the upper layer of mature soil and the bottom layer of raw soil separately. Before planting, trim the roots well and cut off rotten and split roots. The planting depth should be the same as or slightly deeper than the original burial depth of the seedling. When backfilling, first backfill the mature soil, then the raw soil, and carry out "three burials, two tramplings and one lifting of the seedling." Trunk cutting can be done immediately, or 10 days after planting (this allows the sap in the seedling stem to flow back to the roots and benefits root growth), and the trunk-cutting height is 2-3 cm above the ground. After trunk cutting, build up a mound of soil to cover it well.