Nutrient Management for Litchi in Guangdong

The objectives of this study were to understand nutrient requirement and allocation in litchi as well as its rooting soil volume. To fulfill these objectives, two representative types of 15-year-old adult litchi trees (Guiwei and Feizhixiao) were dug out from two well-managed litchi plantations before harvest. Root length, weight, and spatial distribution in the soil were measured, and nutrient uptake and allocation within the plant were analyzed. Field experiments were also set up to test optimal fertilizer rates on litchi yield and quality. The results obtained from this experiment will be used to develop the best nutrient management options for litchi, including specific techniques for soil sampling.

To produce 100 kg of fruit, the Guiwei variety required the following applications per tree: 0.90, 0.92, 1.09, 0.91, 0.13, and 0.16 kg from a mature stand, each of N, P, K, Ca, Mg, and S as well as 17.10, 9.60, 0.56, 1.34, 1.39, and 0.0004 g of Fe, Mn, Cu, Zn, B, and Mo, respectively. The Feizixiao variety has a comparatively higher demand, as follows: 1.25, 0.37, 1.94, 1.36, 0.16, and 0.22 kg of N, P, K, Ca, Mg, and S plus 29.25, 3.24, 0.82, 3.01, 1.69, and 0.003 g of Fe, Mn, Cu, Zn, B and Mo, respectively. Nutrients removed by 100 kg of Guiwei fruits at harvest were 192, 30, 338, 40, 22, 22, 0.67, 0.65, 0.15, 0.35, 0.22, and 0.0003 g of N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, B, and Mo, respectively. For Feizixiao, all the nutrients were taken up in equivalent amounts with the exception of K, Mn, and Mo, which were twice the values observed for Guiwei. In terms of nutrient allocation in the plant, N, P, K and Cu were mainly accumulated in trunk, followed by the leaves and fruit; Ca was largely found in the trunk; Mg, S, Fe, Zn, and B in trunk and leaves; Mn in the leaves; and Mo was split between the fruit and leaves. The spatial rooting distribution was confined within a 6 m diameter and 0 to 70 cm or 0 to 50 cm depth for Guiwei and Feizixiao, respectively.

The information generated from this study greatly improves our in-depth understanding of the nutritional characteristics of two distinct litchi varieties and will lead to significant improvements in nutrient management within the province. Guangdong-BFDP 09