**Author details**

Studies have shown that eucalyptus planted forests can deposit 7–84 tons of dry matter to the soil during 7 years, from old dead branches and dry fruits (25–30%), barks (10–15%) and leaves

The treetops begin to close between the 1st and 2nd year after planting, and the competition causes the disposal of branches and lower leaves that are gradually deposited on the ground. The trees are taller and with small treetops from the 3rd to the 4th year, occurring the deposition of barks. However, the quantities of residue deposited to the ground depend on the eucalyptus species, climate, and evapotranspiration. The components of the eucalyptus forest deposited to the ground are called litterfall, which has great influence on the nutrients availability to the

Thus, considering that the estimated content of nutrients accumulated (in relation to the total accumulated in the plant) in the tree tops and eucalyptus bark after 6.5 years has on average 65% of N, 70% of P, 64% of K, 79% of Ca, and 79% of Mg [128], considerable amounts of nutrients are deposited to the ground and are considered in the fertilization management. In addition, the harvest of trees leaves in the area large amounts of residues such as leaves, branches, tree tops, and small trees discarded during harvest. The trees can be pruning and strips in the area or at companies, depending on the harvesting modules used. Some companies separate the so‐called woody debris (thick branches, tree tops and small trees) and sell as wood or trans‐ formed into wood chips to produce biomass fuel for the company itself, depending on the

However, we must emphasize here the importance of the retention of crop residues in the area because during the harvest the accumulated litterfall on the soil surface has order values of 8– 14 t/ha [129, 130]. Studies have been shown that lower amounts of nutrients are required in fertilization when the bark is left in the field at harvest [131–133]. Moreover, the roots also remain in the area, since that the currently practice of stump removal is increasingly scarce

The crop residues have nutrient availability potential remaining in the area and can reduce the impact on the soil due to the heavy‐machinery used [134, 135]. This is an important fact, since forestry operations can alter the physical and mechanical properties of the soil [136], increasing soil compaction. The productivity of eucalyptus forests may reduce with increasing soil compaction levels [137, 138], due to: (*i*) physical obstruction of developing roots; (*ii*) lower

Many factors influence the residue decomposition rates in the soil, with later nutrients availability for plants as we mentioned in the item 2. Generally, the leaves have faster biode‐ gradation, since they have C/N ratios of 25–45 and C/P of 250–300, while the branches and trunk have C/N of 350–500 and C/P of 500–700 and the barks have C/N of 150–250 and C/P of 300–450 [127]. However, the nutrients allocated in the residues will not be fully available for eucalyptus plants; thus, many companies conduct tests in their crop areas trying to estimate the decomposition rates of the plant compartments and the recovery rates of applied fertilizers. Many companies use these data to establish the complementary fertilization management,

(55–65%) [128].

72 Organic Fertilizers - From Basic Concepts to Applied Outcomes

eucalypt [127].

demand.

due to the large impact on the soil.

water and nutrients absorption; (*iii*) gas exchange reduction.

seeking to minimize costs and make a more sustainable system.

Rafael Vasconcelos Valadares\* , Lucas de Ávila‐Silva, Rafael da Silva Teixeira, Rodrigo Nogueira de Sousa and Leonardus Vergütz

\*Address all correspondence to: rafaelvvaladares@hotmail.com

UFV, Federal University of Viçosa Campus de Viçosa, Avenida Peter Henry Rolfs, s/n, Viçosa – MG, Brazil
