The impacts of post plantation management practices on growth and survival rate of selected tree species in Mirab Abaya District, Southern Ethiopia: An experimental approach

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INTRODUCTION
Deforestation causes the world's natural forest area to shrink from time to time (Moges et al., 2010). As a result, forest goods are in short supply, and the ecology is deteriorating. Many of these issues are addressed by forest plantations. Every year, 4 million hectares of plantations are planted around the world (Brown, 2009;Cossalter and Pye-Smith, 2003). Plantations that are intensively managed are profitable and provide their owners with competitive financial returns (Siry et al., 2005). Forest plantings relieve strain on surviving natural forests, restore degraded regions, and boost soil fertility (Tesfaye et al., 2016). Plantation forests help many people in developing countries better their livelihoods by providing raw materials for wood-based processing industries and customers in both developed and developing countries (Chamshama et al., 2009). Eucalyptus and Acacia species are the most common fast-growing and short-rotation plantation species in the tropics and subtropics (FAO, 2009). The change of land use from forest cover to cultivated land may delay addition of litter, losses nutrient content in soils (Ozgoz et al., 2013), increases rates of erosion (Kassa, 2003;Biro et al., 2013), loss of soil organic matter and nutrient (Saha and Kukal, 2015) and accelerate rate of soil degradation (Barua and Haque, 2013). According to Ogeh and Osioman (2012), decline in organic matter and nutrient lead to decline in soil fertility if replenishment with inorganic or organic fertilizer is inadequate. In Ethiopia, rapid population growth and environmental factors lead to the conversion of natural forest and grass land into cultivated farmland (Gebreyesus, 2013). Such human-caused factors have contributed to soil degradation and loss by deteriorating soil physical and chemical properties, making the ecosystem more delicate and vulnerable to land degradation.
As a result, forest cover of Ethiopia has been decreasing since 1990. Even though, massive reforestation, afforestation, soil, and water conservation activities were launched in the country, their growth and survival rate were poor (Reusing, 2000;Mehari, 2005). According to Tadesse (2012), since 2007, massive tree planting campaigns have been undertaken in connection with the celebration of the country"s Millennium, and about 2.21 billion seedlings were planted in 2009 in four regions: Oromia, SNNP, Amhara and Tigray. Reforestation goals were set in terms of number of seedlings to be planted rather than their ecological requirements (Mehari, 2005). As a result, reforestation impacts could not match with the deforestation rates in which poor implementation and follow-up of plantations have limited their success.
Most plantations in Ethiopia are carried out in harsh circumstances due to a lack of accessible land (Zobel and Talbert, 1984;Evans and Turnbull, 2004). Adverse environments are sites that are marginal for growing economic crops due to their extreme climate and poor soil conditions (e.g. nutrient deficit, acidic and alkaline soils). Moreover, the soils of Ethiopia highlands are shallow due to erosion. Every year, the region losses about 1500 million tons of its topsoil (Hurni, 1993). As a result, most of the soils of highlands of Ethiopia are acidic and their pH ranges between 3 and 5.3 (Tadesse, 2013).
According to the study of Reusing (2000), forest cover of Ethiopia during 1990s was 35 to 40%. In 2010 it was decreased to 11.2% (FAO, 2010) due to the conversion of forest lands into agricultural lands, settlements and increment of demand for construction and fuel wood.
Recently, forest coverage of Ethiopia stands at 15%, but through the new program it is expected to grow to 20% by 2020, while 22 million hectares of degraded land is expected to be rehabilitated by 2030. The forest sector"s contribution to national GDP is also expected to grow from 4 to 8% by 2030 (UNDP, 2019). Establishing forest plantation on degraded land can play a key role in harmonizing long-term forest ecosystem of rehabilitation or restoration goals (Lamb, 1998). Warren et al. (2005) state that successful seedling establishment and growth are dependent on soil condition and stored soil moisture to ensure survival into the following growing season.
Application of organic manures on planted tree seedlings is one of the post plantation management activities that can improve growth and survival rate of planted tree seedlings (Mohammad et al., 2012). In addition, Totey et al. (1986), reported that the adequate quantity of farmyard manure can improve both growth and survival rate of planted tree seedlings better than chemical fertilizers. In addition, seedling quality can also affect the growth and survival rate of tree seedlings (Chavase, 1980). Sorecha (2017) reported that the survival rate of Olea europaea Mill P.S Green was 38% due to lack of after care (post management practices). On the other hand, this tree species can resist harsh environment with some management interventions. According to Kitaba et al. (2017), the survival rate of Cordia africana was poor and accounted 40% due to the shortage of soil nutrients in degraded watersheds. In addition, farmers prefer Eucalyptus spp. rather than indigenous tree species due to short rotation income and their capacity to grow rapidly even after harvesting. However, the growth and survival rate of indigenous and exotic tree species can be improved by applying soil amendments like inorganic, organic manures and  (Amha et al., 2020). The primary goal of this study is to evaluate the effects of farmers' postmanagement practices, such as soil amendments, on the growth and survival rate (growth of height, root collar diameter, and survival rate) of planted tree seedlings, to identify the tree species with the highest growth rate of root collar diameter and height among selected tree species, and to describe some physical and chemical properties of the soil in the study area.
The district has three agro ecological zones: Dega (high altitude area of land), Weina dega (mid altitude area of land) and Kolla (low altitude area of land). Out of 24 kebeles, 16 (62%) are in low land, 6 (27%) are located in mid lands and 2 (11%) are found in high lands. According to the Ethiopian National Meteorology Agency, the average annual rainfall is between 700 and 1600 mm and means maximum and minimum temperatures of 22, and 7°C, in Chencha Woreda and Mirab Abaya areas, respectively. The Woreda experienced a bimodal pattern of rainfall regimes (belg from March to May and meher from July to September). The main cropping season in Kolla agro ecology is belg that is from March to May, but high land areas receive the highest rainfall during the meher (June to August) ( Figure 2).

Seeds collection of selected tree species
Seeds collection of selected tree species, C. africana and O. europaea were collected from home gardens, Cupersus lusitanica seeds were collected from communal plantation site that is located at an altitude of 1100 masl and Gravilea robusta seeds were obtained from a project plantation. Finally, each of tree seeds were sown based on the nursery calendar. Sowing, transplanting and out planting of selected tree seedlings were presented (Table 1).

Seedlings preparation
About 800 seedlings of four multipurpose tree species: C. africana, O. europaea, C. lusitanica and G. robusta were prepared, graded and out planted in early June in experimental site in Morode kebele. 1600 kg of FYM was collected on 04 -06 January, 2019 from the study kebele near the study area stored and well decomposed for 5 months before plantation period of the selected tree seedlings in the temporary shed in the experimental site (Bradshaw, 1997). A 2 kg farmyard manure FYM was applied on 400 seedlings (that is, 200 seedlings received only FYM and 200 seedlings received both urea and FYM).
12.5 kg urea was brought and 10 kg of it was applied to 400 seedlings (that is each seedlings received 25 g urea based on the result of soil test). Spacing of plantation for selected tree seedlings was presented (Table 2).

Soil sampling methodology
In experimental site, Sutte microwater shed, Morode kebele, random selection of points was chosen to withdraw soil samples from three successive depths (0-15, 15-30 and 30-45 cm). Soil samples were taken using soil auger following zigzag method of soil sampling in 10 m distance intervals (Bradshaw, 1997). The soil cores from 10 depths were mixed to make 3 soil composites (1 kg from each successive depth). Soil samples were taken to Arba Minch University for analysis of bulk density, pH, total nitrogen (TN), available nitrogen (N), available phosphorus (P), available potassium (K), cation exchange capacity (CEC) and soil textures and micronutrients like Copper (Cu), Zinc (Zn) and Iron (Fe).
Randomized Complete Block design with four blocks with two replications and three treatments (Urea alone, Farmyard manure (FYM) and Farmyard manure and urea (FYM + Urea) and Control were applied to those selected tree species in the study experiments. The blocks were constructed from east to west along the contour and divided into 8 plots. Totally 32 experimental units or plots have 25 seedlings planted in 2 m by 2 m spacing and total of 800 seedlings in experimental site. A species was represented by 200 seedlings randomly planted in these 32 experimental units.

Qualitative data collection
Qualitative data were collected, using purposive sampling method in which focus group discussion with twelve farmers who are involved in tree planting, three agricultural development agents and seven experts of plant science and natural resource management or key informants (that is, from agricultural and natural resource management office).

Quantitative data collection
Initial tree seedlings height and root collar diameter were measured using meter tape before out planting. Growth of height, root collar diameter and survival rate were taken each month by nondestructive method (Van et al., 1998) using systematic sampling technique .

Data analysis
Survival rate was calculated for each tree species planted in the experimental site using the formula (Megan, 2013): Mortality rate = Number of seedlings dead during study period/Total number of saplings planted in each period × 100 Survival rate = 100 -Mortality rate (1) Survived seedlings were counted, and their survival rate was calculated within month starting from August 2019 to June 2020 for 12 months.
Mean and multivariate analysis of variance were used for data analysis using SPSS version 20 at 5% level of precision was applied to know whether height growth, root collar diameter and survival were significantly different. Soil sample results were analyzed using different methods. Total nitrogen (TN) using Kjeldahl method, followed by calculating available nitrogen from total nitrogen or the concentration of nitrate nitrogen that accounts only 2% of TN (Bremner and Mulvaney, 1982). Finally, the quantity of urea-nitrogen in kg per hectare was calculated (Karuku and Mochoge, 2018) using the following formula: kg N/ha = Soil depth × Bulk density × Conc. (μg N) × Area (cm 2 ) / Weight of soil × 10 9 (2) where kg N/ha is the total nitrogen in kg in study experimental area (40 × 80 m) area and Conc. (μg N) is the concentration of total nitrogen in microgram (400 μg) using conversion factor 1% = 10000 ppm or 10000 μg N. Finally, total fertilizer need for planted tree seedlings was analyzed using Oldham (2017) formula as follows: Total nitrogen need = Recommended nitrogen in lbs / Nitrogen content fertilizer × Area in square feet /1000 square foot Available phosphorus (P) according to Olsen and Sommers (1982), organic carbon (OC) by Walkley and Black (1934), cation exchange capacity (CEC) by Rhoades (1983). Soil pH was analyzed using a potentiometric measurement method on the supernatant suspension of 1:2.5 water to soil ratio (Rhoades, 1995). The moisture content of soil samples was estimated after an immediate sampling of soil based on oven-dry method. Among many of soil physical properties, soil texture, soil moisture content and bulk density were studied. Soil texture was determined by sieve method (Yitbarek et al., 2016) and bulk density by the core method from the oven dry at 105°C (Landon, 1991). Soil moisture content was determined by gravimetrically through oven drying at 105°C to a constant weight from known mass and volume of soil sample collected using soil moisture cans.

C. africana
An initial average height of seedlings of C. africana was 28 cm and average root collar diameter was 0.51 cm, respectively. The seedlings C. africana treated with urea, FYM and combination of FYM and urea increased growth of height and root collar diameter dramatically over control (Table 3). Over a period of seven months, plots previously received urea alone and the combination of urea and FYM showed poor growth of height and root   (Table 3 and Figure 3A) and growth of height and RCD was highly significant at P=0.05. The height growth and root collar diameter of Cordia was highly stunted in plots that received no fertilizer and urea. This might be associated with leaching of urea during the period since there was high rain fall, toxicity of Cu and Zn (nutrients may vary even in small distance) and coarse sand (texture may also vary in small distances). These results were related to the findings of Tefese (2007) in that the mean height and RCD of C. africana in clay loam soil and Gebeyehu (2017) in nitosoils, respectively. C. africana seedlings treated with FYM and the combination of FYM and urea showed better growth of height and root collar diameter as farmyard manure reduced the toxicity of Cu and zinc by binding them from the soil (Davis, 1984). In contrast, the lowest height gains of native species in the range of 0.52 m in Albizia gummifera up to 1.20 m in C. africana (Amaha et al., 2020) At the end of the second month count, survival rate for control, urea, FYM and the combination of FYM and urea were 92, 92, 96 and 96%, respectively. Contrary to other tree species, the survival rate was reduced rapidly in control and urea plots from third to the seventh month. From the eighth to twelve-month count, the survival rate was also continuously decreased in all plots. The performance of C. africana during the record of the twelve months for control, urea, FYM and the combination of urea and FYM were 44, 44, 68 and 72%, respectively (Table 3).
As can be seen from the survival rate in each treatment, the least survival rate was recorded in control and urea plots and the higher and the highest survival rate were recorded in plots that received FYM and the combination of FYM and urea. This showed that FYM might improve the water holding capacity that was being affected by sandy texture (Tadesse et al., 2014). Similarly, in clay loam soil, the survival rate of C. africana was 98% in eight months growing period (Tafese, 2007). Likewise, there was a significant effect shown by the application of moringa leaf juice on the field condition on the parameters of height on C. africana tree . There was no significant difference in mean survival rate for seedlings that received FYM, the combination of FYM and urea and control but there was significant difference between mean survival rate of seedlings that received only urea at P=0.05.

Olea europaea
The growth of height and root collar diameter for control, urea, FYM and combination of FYM and urea were increased drastically after forty-five days in planted seedlings, respectively. Starting from the second month of observation, the mean height for control, urea, FYM and combination of FYM and urea were 28.3, 28.4, 35.4 and 37.3 cm, and that of root collar diameter was 0.48, 0.54, 0.64 and 0.67 cm, respectively. This made the growth of height and root collar diameter lag, as a result there was no much change on growth over a period of seven months. Thus, the recorded height was 30.2, 34.7, 44.2 and 46.9 cm and root collar diameter 1.00, 1.01, 1.08 and 1.2 cm, respectively. Twelve months after seedlings planted, the recorded height and root collar diameter for O. europaea in control, urea, FYM and the combination of FYM and urea were increased dramatically in each plot showing better growth in height and RCD in both FYM and urea, respectively (Table 3 and Figure 3B). In addition, according to Amaha et al. (2020) both Acacia saligna and Sesbania sesban achieved the highest root collar diameter growth, while the lowest root collar diameter growth of A. gummifera and O. europaea. Results suggested that O. europaea may be well suited to fine textured soils like loamy, sand, and loamy clay silt loam (Sibbett and Ferguson, 2019). The majority of species relative growth did, however, slow down with time. These findings were consistent with  who noted an earlier height and biomass increment than a later age. According to the result of analysis of variance, there was significant difference in growth of both height and RCD at P=0.05. However, due to their modest growth rates, A. gummifera and O. europaea have the lowest height and root collar diameter growths (Sorecha, 2017). Furthermore, some of these native tree species, the root collar diameter and height in growth tended to be better when planted together than when planted separately.
From forty-five days to the end of the third month, no change on mortality was observed and each planted seedling in experimental site was becoming deep green continuously due to, there was continuous rain fall, however only one seedling was dead in control plot. On the same manner, from fourth to seventh month count, O. europaea showed no change on survival rate such that Table 3. Mean ± standard deviation of the four different tree seedlings growth of height, root collar diameter and survival rate of tree seedlings using urea, FYM and combination of urea and FYM.

G. robusta
The performance of G. robusta during the period of out planting shows the longest and shortest height was 29 and 27 cm and the highest and lowest root collar diameter were 0.64 and 0.38 cm, respectively. Even though, the fourth month growth was affected by heavy rain fall, G. robusta continued to grow in both height and root collar diameter on all the treatments provided. At the end of the year after plantation, the growth of height and RCD for seedlings received urea, FYM and the combination of FYM and urea were 51.21, 72.64, and 78.31 cm over the control (45.16 cm) and 0.79, 1.06 and 1.1 cm over the control (0.8), respectively (Table 3 and Figure 3C). According to the results recorded from experimental site, seedlings received FYM and the combination of FYM and urea showed the highest growth of height and RCD. This result relates to the finding of Karanja et al. (1999) in that annual height and root collar diameter of G. robusta was 77 and 1.8 cm, respectively and Gebeyehu (2017) 80 and 1.02 cm, respectively. In addition, Yakob et al. (2017) reported that G. robusta showed 80 cm height growth in deep dark reddish clay soil and Yeshiwas et al. (2018) reported that farm yard manures and nitrogen fertilizers played an important role on plant growth and development in sandy soil. Growth of height and root collar diameter of G. robusta without treatment was affected by shortage of soil nutrients such as phosphorous, potassium, and nitrogen as well due to toxicity of Copper and Zinc, for successive twelve months (Maliondo et al., 1999). The average DBH and height of the trees showed significant difference under different spacing regimes (Sanjith et al., 2020). Accordingly, the average height and mean annual diametric increment of G. robusta did not exceed when grown in different locations of Uganda (Okorio and Peden, 1992). In addition, Otieno (1992) found that in the Shiaya district, the average height at age 5 ranges from 8.8 to 10.6 m and the height of mean annual diametric increment ranges from 1.8 to 2.1 m, depending on the location and spatial arrangement of the trees. Similarly, G. robusta showed that fertile soil, cover crops, and growing between trees significantly improved growth performance. However, growth was negatively correlated with height above sea level, showing weak growth (Kalinganire, 1996). The numbers of seedlings of G. robusta during the second month in control, urea, FYM and combination of FYM and urea, were all equal survival rate of 100%, respectively. From second to the fifth month count, the number of seedlings of G. robusta recorded for control was 96% compared to treatments 100%, respectively. During this period, there was continuous rain fall at the study site, however, in control and urea plots, two seedlings were dead. Similarly, in line with the survival rate of G. robusta, the highlands of Uganda were maintained at 100% (Okorio and Peden, 1992). By the time of twelve-month period, the mean % survival rate was decreased from 96 to 56% in control, and this reduction of survival is seen in treatments as well (Table 3). In agreement with Kalinganire (1996) the survival rate was between 47 and 68% at the age of two years in G. robusta. The reason might be associated with the domination of sand texture that resulted in low water holding capacity and consequently death of planted seedlings. There was no significant difference (P> 0.05) in mean survival rate of G. robusta that received different treatments as observed for survival and other studied growth characteristics (Madadi et al., 2009).

C. lusitanica
During plantation period, the longest height was 43.2 cm and the smallest height was 36.1 cm. Following this problem, 10 kg of urea was applied to the plots received urea alone and the combination of urea and FYM in C. lusitanica, respectively. From this it is easy to conclude that application of farmyard manure and urea may favour the vigorous growth of height and root collar diameter in C. lusitanica. Twelve months after plantation, growth of height for control, urea, FYM and the combination of FYM and urea was 94.2, 124.1, 144 and 158 cm, respectively and root collar diameter was 0.97, 1.22, 1.64 and 2.27 cm, respectively (Table 3 and Figure 3D). Furthermore, it is easy to understand that FYM together with urea improved the growth of height and RCD of C. lusitanica by over 100 and 1.3 cm faster than planted seedlings compared to control plots, attributed to heavy rains from July 2019 to June 2020, except February 2020 which was partially dry during the study period. Similar range of dominancy in height for C. lusitanica was also observed in the Ethiopian lands (Mamo and Sterba, 2006) and certain areas of Kenya (Ngugi et al., 2000).
The survival percentage of seedlings planted in each experimental unit for control, urea, FYM and combination of FYM and urea was 100%, respectively, but the survival rate for control plots up to the seven months was 86%. From the eight to twelve months count, the survival rate for control, urea, FYM and the combination of FYM and urea were 76, 94, 94 and 100%, respectively. This might be due to the toxicity of zinc and copper in addition to the deficiency of nitrogen, phosphorous and potassium. In accordance with the study of Gill et al. (2009), farmyard manure not only increases growth but also improves soil fertility in soils like sand. The decrease in survival rate in control compared to treatment was caused by nutrient competition or plant death as a result of no thinning (Luoga et al., 1994). There was no significant difference in mean survival for seedlings that received FYM, the combination of FYM and urea and control but there was significant difference between mean survival rate of seedlings that received only urea at p=0.05.

Soil texture, moisture content and bulk density
The current observation indicated that the variation in soil texture was more of sand with 94% compared to clay and silt (Table 4), and the results were compared to soil textural class standards and related to the range of 85 to 100% are sandy soil for the characterization and classification of high land soils in Western and Northern Ethiopia (FAO, 2006;Deressa et al., 2018). The increased percentage of sandy soil in highlands is due to high rain fall, which causes sheet and hill erosion, resulting in fine particles of clay and silts being easily detached and transported, and finally the coarser texture (sandy soil) remaining in the study area. Due to the presence of macropores, this soil diverts more water into the soil profile, has high nutrient leaching: nitrogen (70%), phosphorus (80%), and potassium (63%), tends to have low moisture levels, and affects plant growth (Kebede and Charles, 2009). Because of the presence of macro pores, this soil drains more water down into the soil profile, has high nutrient leaching: nitrogen (70%), phosphorous (80%), and potassium (63%), is prone to low moisture content, and affects plant growth (Kebede and Charles, 2009). The study site had a moisture content of 25.59%, which was compared to the critical levels of soil moisture for sandy soil reported (Table 4) in some degraded areas of Ethiopia (Nyssen et al., 2006). The bulk density of the study site was 0.77 g/cm 3 , when compared with the standard bulk density, which no longer affects plant root penetration, particularly when the bulk density is less than 1.46 g/cm 3 (Hunt and Gilkes, 1992;USDA, 2006).

Soil chemical properties
According to the result of soil test, the concentration of TN was 4% or 400 ppm showing the concentration decreases as the depth of the soil increases (Table 4). This result was in line with the finding of Ayalew et al. (2014) that the concentration of TN was low due to degradation of total nitrogen coupled with little nitrogen fertilization that occurred in the area. In addition, Hailu et al. (2015) reported that the concentration of TN below 0.1% is taken as very low and as a result the soil was poor in quality on the bases of TN which was compared to the standard TN where the level is less than 2% (Landon, 1991). In view of the fact that the plant available form of nitrogen in the soil is dependent on total nitrogen accumulation, where the four tree seedlings planted in this experiment will no longer have enough available nutrients unless additional nitrogen is provided. For the sake of nitrogen recommendation as fertilizer for plants, converting the total nitrogen into the plant available nitrogen form is crucial and important (Karuku and Mochoge, 2018). However, according to Angus (2001), the available form of nitrogen in the soil accounts for only 2% of total nitrogen (98% is the unavailable form of nitrogen). Furthermore, the established rule of thumb for available nitrogen or the plant utilizable form of nitrogen in tropical countries ranges from 1 to 3% of total nitrogen. According to the results, available phosphorus in the soil was 2.09 mg/L which demonstrated that concentration is very low for the tree seedlings planted (Table 4), where the soil test result was compared to the standard level of available phosphorus which is less than 3 ppm (USDA, 2001;Landon, 1991). Unlike nitrogen, phosphorous cannot be leached down the soil profile, but it can be washed from the soil by water and runoff (USDA, 2001). The lower level of available phosphorous was caused by a lower concentration of organic carbon in the study site. This, in turn, may influence the growth of planted tree seedling in the area.

Soil pH and soil organic matter
The pH of the surface and subsurface soil profiles analyzed did not differ significantly (Table 4). The mean soil pH of the study site was 6.95 which shows, the soil was neutral that may no longer affects growth of planted tree seedlings when compared with the standard pH range of 5.5 to 7studied by Landon (1991). This could be due to the increased organic matter in the topsoil, which may have increased the soil's buffering capacity and thus resistance to changes in soil pH. Despite a significant difference in cations between soil layers (Table 4), there was no significant change in pH, which could affect the planted tree seedlings.
The result of organic carbon was 1.41% in some parts of Ethiopia, the concentration of organic carbon shows great variation between degraded lands and forested lands. According to the finding of Amare et al. (2013), in heavy rain fall areas of Ethiopia like Anjeni the lowest organic carbon recorded was 0.2% in cultivated field and 13.68% in top soil of old forest. In addition, in areas like Wondogenet (Agroforestry based farming system) and Bale (Bale mountain National Park) both having high rain fall and soil organic carbon obtained was 3.37 in the study site which is low due to lack of vegetation cover with poor in quality as a result it may hinder plant health and growth.
The soil organic matter was 2.82% which was related to the findings of Corral-Nunez et al. (2014) in some protected and restored Northern parts of Ethiopia over 20 years. Similar findings were seen according to Olsenand Sommers (1982) where the concentration of soil organic matter was 5.6%. However, in cultivated areas its concentration was very low (2.1 to 2.9%) as presented (Table 4). From this, it is easy to understand that study area is affected by shortage of soil organic matter that might result in poor soil quality to reduce growth and survival rate. The concentration of soil organic matter was higher at the surface than in the subsurface soil due to the higher amount of organic carbon at the surface than in the subsurface soil of the study area. This could be due to increased organic matter deposition (leaf litter, root) under trees and in the topsoil, as well as increased biological activities that promote organic matter decomposition and subsequent mineralization (Nega and Heluf, 2009).

Cation exchangeable capacity (CEC)
Cation exchange capacity is a useful indicator of soil fertility because it shows the soil ability to supply three important plant nutrients: calcium, magnesium and potassium. The result of cation exchange capacity was 13.2 mg/L which is medium (Mojiri et al., 2012), while comparing with the standard level of CEC that is the range between 5 and 15 mg/L ( Table 4). The decrease in soil CEC values in farmland uses was primarily due to a decline in organic matter content (Nega and Heluf, 2009). According to the exchangeable cation and acidity test results, calcium and potassium were much lower than magnesium and sodium ( Figure 4). However, Nicholas (2004) research found in line with that of exchangeable cation levels, such as potassium and sodium, were higher than normal.
The soil test results showed that the concentrations of Cu, Zn, and Fe at the experimental site were 1.18, 3.2, and 1.95 ppm, respectively (Table 4). These results were compared to the critical levels of the nutrients in the soil (Lanyon et al., 2004), where the concentration of Cu and zinc were high compared to concentration of Fe which was adequate (Jones, 2003). Hence, the level of Fe in the study site was suitable for planted tree seedlings growth but the elevated concentration levels of Cu and zinc might be one of the reasons for stunted growth of planted tree seedlings because the toxicity of zinc resulted in symptoms like chlorosis and low production of biomass (Marschner, 2011). According to authors, it was observed that increased organic matter may improve soil structure, aeration, and protect micronutrient oxidation and precipitation. Additionally, soluble chelating agents may help also to increase the solubility of micronutrients.

Conclusion
The preliminary evaluation that the C. lusitanica outperformed in terms of height, RCD and survival rate for twelve months after planting suggested that C. lusitanica is suitable for forest rehabilitation in the study area, and that this reforestation effort could yield positive results in the long run. Another possible reason for the significant growth rate in height and diameter associated with the high survival rate of C. lusitanica could be the adaptability of planted trees to grow in specific soil conditions (sandy soil). In addition, the ability of FYM to continuously release soil nitrogen, phosphorus, and potassium and similarly improve soil water-holding capacity was also compared to C. africana, which has the lowest survival rate. This could be due to the low resilience of sandy soil during the growing season, particularly in control plots where seedlings were damaged by nitrogen, potassium, phosphorus deficiencies, and copper and zinc toxicity. Similarly, urea had poor growth and survival rates, although they did better than control plots. Since there has been heavy rainfall throughout the year except in the month of February, this could be due to leaching of urea during the growing season. Fertilizer recommendations for tree species based on soil test must be a prerequisite issue not only to improve growth and survival rate, but also to reduce problems of over application (soil acidity) and underapplication (poor growth and survival rate) of planted tree seedlings. Well-prepared farmyard manure can boost growth in height, root collar diameter, and survival rate. As a result, more research is needed to determine the soil plant relationship of these tree species as well other edaphic factors that may affect the growth and survival of tree species under line planting technique.