Monitoring fine root growth to identify optimal fertilization timing in a forest plantation: A case study in Northeast Vietnam

Abstract

Fertilizer is applied widely to improve the productivity of plantations. Traditionally, fertilization is conducted in spring and/or in the early rainy season, and it is believed to support the growth of planted trees in the growing season. Little attention to date has been paid on identification of the optimal timing of fertilization and fertilizer dose. In this study, application of the fine root monitoring technique in identifying optimal fertilization timing for an Acacia plantation in Vietnam is described. The study used two fertilizer doses (100 and 200 g NPK/tree) and three fertilization timings (in spring; in the early rainy season; and based on the fine root monitoring technique to identify when the fine roots reach their growth peak). As expected fertilization timings significantly affected growth and above-ground biomass (AGB) of the plantation. Fertilization based on the fine root monitoring technique resulted in the highest growths and AGB, followed by fertilization in the early rainy season and then in spring. Applying fertilizer at 200 g NPK/tree based on the fine root monitoring technique increased diameter at breast height (DBH) by 16%, stem height by 8%, crown diameter (Dc) by 16%, and AGB by 40% as compared to early rainy season fertilization. Increases of 32% DBH, 23% stem height, 44% Dc, and 87% AGB were found in fertilization based on fine root monitoring technique compared to spring fertilization. This study concluded that forest growers should use the fine root monitoring technique to identify optimal fertilization timing for higher productivity.

Acacia Plantation Development and the Configuration of Tree Farmers’ Agricultural Assets and Land Management—A Survey in Central Vietnam

“…Such risks are highest during the wet season (in TTHP from late September to December [152]) when strong monsoon rainfalls and occasional typhoons are frequent. Correspondingly, the timing of tree harvesting, post-harvest plot management (plant residue management, use of fire, soil compaction with trucks and machinery), inter-rotation period, and the timing and practices of plot replanting (planting technique, fertilizer uses) all exert non-negligible influences on the magnitude of soil erosion risks [95,129,132,[153][154][155].…”

“…Low levels of soil phosphorus (P) exert significant limitations on plant growth in the rainforests of TTHP [157]. Accordingly, P is an important plant nutrient influencing woody growth on (historically rainforest-covered) soils in acacia plantations, especially during early growth after replanting [155,158,159]. In Vietnam, acacia farmers using fertilizers typically apply 100-200 g of an NPK fertilizer per tree mix at planting, whereby the effects of nitrogen (N) and potassium (K) are poorly understood.…”

Contribution of Litterfall to Aboveground Net Primary Production in Acacia hybrid Plantation, Northeast Vietnam

“…The soil at the site is classified as Ferralic Acrisol with a depth of 60-70 cm. At the time of the experiment, the soil had a pH of 3.6, organic matter of 2.6%, Nitrogen of 0.18%, and Phosphorus of 2.1 mg P 2 O 5 /100 g soil [20].…”

Transcriptomic Analysis of Fertilization Effects on the Biosynthesis of Sesquiterpenes in Essential Oils from Phoebe Bournei Twigs and Leaves

“…Fertilization is a common and effective method to increase plant biomass [27][28][29] and has a certain impact on the composition and biological activity of plant essential oil [30]. Fertilization can not only promote the growth of plants, but also modulate the composition of essential oil, thus changing the EO biological activity, to some extent [31].…”