Influence of Organic Fertilizers on the Early Growth of Tamarindus indica L

Inadequacy of information on the early growth responses of T. indica seedlings to manure sources has limited its propagation. In an attempt to enhance the growth of T. indica, an investigation was conducted to assess the influence of organic fertilizers on the growth of T. indica . The experimental design adopted was a Completely Randomised Design with six treatments replicated five times. The treatment consisted of 10g of each manure (cowdung, goat droppings, rabbit droppings, poultry droppings, pig droppings and control) assessed on the early growth of T. indica seedlings. Six months old T. indica seedlings were transplanted into pots with and without manure and subjected to 200ml of water daily. Data collected were subjected to Analysis of Variance (ANOVA) at 5% level of significance. Results obtained showed that manure sources significantly (P<0.05) enhanced the growth of T. indica . Significant height (27.82cm), number of leaflets (67.00), total fresh weight (5.57g) and total dry weight (2.54g) were recorded from seedlings planted in the soil amended with goat droppings respectively at 12 weeks after transplanting. Highest girth (0.33cm) and significant leaflet area (9.98cm 2 ) were recorded from seedlings planted in the soil improved with cowdung and poultry droppings respectively at 12 WAT. Goat droppings enhanced the growth of T. indica seedlings.


Introduction
In the humid tropics of West and Central Africa, forest tree species provide an array of medicinal, nutritional and industrial produce, which are of direct relevance to the well-being of the people (Gbadamosi and Oni, 2004;Kokutse et al., 2014;Alaba et al., 2015). Most of these woody perennials have multiple uses, and wherever grown, they are highly valued by the local farmers (Atangana et al., 2014). One of the indigenous woody perennials is Tamarindus indica, an indigenous economic tree species that is widely distributed in Sudan and other Afro-Asian countries (Warda et al., 2007). The species is indigenous to tropical Africa, particularly in the Sudan (Morton, 1987). Adeola and Aworh (2010) stated that Tamarindus indica grows wild in Africa in locales as diverse as Sudan, Cameroon, Nigeria, Zambia and Tanzania.
In Arabia, it is found growing wild in Oman, especially Dhofa, where it grows on the sea-facing slopes of mountains. Lewis et al. (2005) stated that Tamarindus indica is a member of the family Fabaceae, sub-family Caesalpinioideae which is the third largest family of flowering plants with a total of 727 genera and 19,327 species. The tree is commonly known as "tsamiya" in Hausa, "Icheku Oyibo" in Igbo, Ajagbon" in Yoruba, and "Tamarind" in English languages. The species is valuable and more of it needs to be propagated. The slow growth characteristics of T. indica have limited its propagation. Bello and Zubairu (2015) stated that the T. indica is a slow-growing one. The slow growth of seedlings of T. indica is a threat to population demand and biodiversity conservation.
The growth of T. indica needs to be enhanced by fertilizers. The use of inorganic fertilizer has been implicated with negative consequences such as nitrate leaching, groundwater pollution, degradation of soil structure and decrease surface water infiltration (Pondel et al., 2001). The unavailability and unaffordability of inorganic fertilizers make a strong case for the use of alternatives obtained from organic sources (Dianda et al., 2009;Oviasogie et al., 2013). Thus, farmers and tree growers are seeking alternatives such as the application of organic fertilizer for the correction of nutrient deficiencies in agriculture and forestry (Tanimu et al., 2007;Agele et al., 2016). FAO (1994) recommended that any fertilizer material of organic origin must have nutrient such as N, P and K. These suggest that organic fertilizers are very suitable as alternative sources of nutrients for seedlings in nursery production.
They are obtained from the composting or processing of organic materials from plant (crop residues, seaweed), animal (poultry droppings, cow dung), urban/industrial (municipal wastes) and microbial sources (fungi). These organic fertilizers have been successfully used for soil enhancement in arable crop production and could potentially be explored in raising of tree seedlings (Omisore et al., 2009). Organic fertilizers are biodegradable and easily decompose, being broken down into smaller and soluble particles by the microbial community (Aderounmu and Olajuyigbe, 2019). Hence the use of organic fertilizer in the nursery portends advantages such as soil replenishment, increased soil friability, improved beneficial soil life, increased growth and yield, prevention of hardpans, recycling and reduction of waste, minimized greenhouse gas emissions, and plant protection against diseases. et des excréments de volaille respectivement à 12 WAT. Les excréments de chèvre ont amélioré la croissance des semis de T. indica. Mots clés : Croissance des plantes, engrais organique, amendement du sol, arbres fruitiers indigènes The increase in soil organic matter resulting from manure application helps to reduce the impact of rainfall, surface run-off and erosion. Higher quality and quantity of organic matter also improve soil fertility by enhancing the supply of nitrogen, phosphorus and potassium. Organic matter helps to maintain soil structure and moderate soil temperature, while slowly releasing nutrients and reducing the risk of leaching. Agera et al. (2019) reported that organic manure decreases the danger of over-fertilization because the nutrients are released slowly. These attributes tend to increase seedling performance particularly in the nursery (Ipinmoroti et al., 2006;Oviasogie et al., 2013). The increased seedling performance requires knowledge of nursery management. In plant nursery management, the nutrient requirements of tree species differ. Hence efforts are required to identify the appropriate fertilizers that could enhance each plant growth (Nwoboshi, 2000). Little information is available on the use of organic fertilizer to boost the growth of T. indica. In this light, this investigation was conducted to assess the influence of organic fertilizers on the early growth of T. indica.

Experimental Procedure
The seeds were sourced from Afaka Forest, Kaduna State. Three hundred seeds were extracted from fruits and air dried for thirty minutes. The viability of the randomly selected seed samples were assessed using the cutting method (Schmidt, 2000). The sowing media (river sand), which was collected from the floor of the College dam was made to pass through 2mm sieve and then sterilized at 160 o C for 24hours. The polythene pots used were 20x10x10cm 3 in dimension and filled with sterilized river sand and arranged in the screen house. After six months of germination of seeds, uniform seedlings were available for the growth experiment.

Influence of organic fertilizers on the early growth of Tamarindus indica
The experimental design adopted to determine the influence of organic fertilizers on the early growth of Tamarindus indica was a Completely Randomised Design with six treatments replicated five times. The treatment consisted of 10g of each organic fertilizer (Cowdung, goat droppings, rabbit droppings, poultry droppings, pig droppings and control) applied on the T. indica seedling growth. The experiment involved a total of thirty seedlings. Six month old seedlings were transplanted into potting mixture with or without manure and subjected to 200ml of distilled water daily. Seedlings planted in sand without mixture of manure served as control. Growth parameters assessed every three weeks included; Seedling height (using meter rule); girth (using viener caliper); the number of leaflets were counted manually. Leaflet area was obtained by linear measurement of leaflet length and leaflet width as described by Clifton-Brown and Lewandowski (2000). LA=0.74xLxW (1) Where, LA =Leaf area=Product of linear dimension of the length and width at the broadest part of the leaf. The fresh and dry weight were determined by the use of Mettler Top Loading Weighing Balance, but dry weight was taken from oven dried seedlings at 70 o C for 72hours (Umar and Gwaram, 2006).

Data analysis
The data on the influence of organic fertilizers on the early growth of Tamarindus indica were subjected to one way analysis of variance (ANOVA) using SAS (2003). Comparison of significant means was accomplished using Fishers Least Significant Difference (LSD) at 5% level of significance.

Results
A significant height of 27.82cm was recorded from seedlings planted in the soil influenced with goat droppings at 12 weeks after transplanting (WAT). The least value of height (14.24cm) was recorded from seedlings planted in the unamended soil (control) at 3 WAT (Table1). A significant number of leaflets of 67.00 were recorded from seedlings planted in the soil enhanced with goat droppings at 12 WAT. The least value of number of leaflets of 16.60 was recorded from seedlings planted in the soil without influence of manure (control) at 3WAT (Table 2). There was no significant (P>0.05) difference among the girths of seedlings enhanced with and without organic fertilizers at 3 to 12 WAT. Highest girth of 0.33cm was recorded from seedlings planted in the soil amended with cowdung at 12 WAT. The least value of 0.18cm was recorded from seedlings planted in the soil without amendment of organic fertilizers (control) at 3 WAT (Table 3).  A significant leaflet area of 9.98cm 2 was recorded from seedlings planted in the soil amended with poultry droppings at 12 WAT. The least value of 4.84cm 2 was recorded for leaflet area of seedlings planted in the soil without the influence of organic fertilizers (control) at 3 WAT (Table 4). Significant total fresh weight (5.57g) and total dry weight (2.54g) were recorded from seedlings planted in the soil improved with goat droppings. The least values of 2.95g and 1.36g were recorded for total fresh and dry weights of seedlings planted in the soil without amendment of organic fertilizers (control) respectively (Table 5).   Table 6: Nutrient composition of manure sources applied

Discussion
Significant growth parameters were recorded from seedlings planted in the soil improved with goat droppings. A similar observation has been made by Khaple et al. (2012) who stated that among the organic nutrients treatments of Grevillea robusta, goat manure was found to be the best which produced highest growth parameters. It could be inferred that goat manure enhances the growth of plants. Similar observations have been made by Duarsa et al. (1996), Maerere et al. (2001), Awodun et al. (2007), Gichangi et al. (2010) and Usman (2015). The ability of goat manure to enhance the growth of T. indica seedlings relative to others could be adduced to its release of potassium better than others. The result of this investigation revealed that goat manure contained the highest amount of potassium which influenced the growth parameters of T. indica seedlings. The essential characteristics of its potassium content accounted for highest growth parameters of T. indica planted in it.
Potassium is an essential element that functions in the activation of enzymes (Mengel et al., 2001;Marschner, 2012), the translocation of photosynthates and the synthesis of cellulose, a building block of every plant cell wall (Anghinoni and Bissani, 2004;Havlin et al., 2005;Sardans and Penuelas, 2005;Pettigrew, 2008;Wang et al., 2013), transplant of sugars from leaves to fruits, and production and accumulation of oils (Romheld and Kirky, 2010), turgor regulation within the guard cell during stomatal movement (Wang et al., 2013). Xu et al. (2020) reported that appropriate potassium supply enhanced photo assimilates transport from leaves to roots as well as from roots to leaves and increased nitrogen use efficiency (NUE) by influencing photosynthesis, C and N metabolizing enzyme activities, nitrate assimilation gene activities, and nitrate transport. It plays an important role in yield and quality improvement (Marschner, 2012;Oosterhuis et al., 2014), cell growth (Hepler et al., 2001) and growth and development of plant roots (Xu et al., 2020). An efficient potassium status may facilitate osmotic adjustment which maintains higher turgor pressure, relative water content and lower osmotic potential, thus improving the ability of plants to tolerate drought stress (Kant and Kafkafi, 2002;Egilla et al., 2005).
Among the fertilizers investigated, goat manure gave highest growth parameters of T. indica seedlings. Contrary to the result of this investigation, various researchers have reported diverse responses of manure to the seedlings of forest tree species. Egbewole (2017) reported highest growth parameters for Araucaria heterophylla seedlings planted in soil treated with poultry droppings. Albizia zygia and Blighia welwitschii, seedlings had the best results in soil treated with 6g of composite fertilizer, while Lophira alata and Pterocarpus soyauxii seedlings showed best growth in soils treated with 9g of composite fertilizers for all other parameters (Andrew et al., 2019). Buochuama and Akhabue (2020) stated that cow manure enhanced the growth of Streculia setigera seedlings. Thus cowdung could be utilized to make nutrient available for optimal growth of Tamarindus indica seedlings (Sodimu et al., 2020). Rotowa et al. (2020) recommended the use of poultry droppings in raising Eucalyptus torelliana.
The use of fish pond sediment as organic manure enhanced the growth of Dennettia tripetala seedlings (Anozie et al., 2020). Agera et al. (2019) recommended poultry droppings as the most suitable organic manure for nurturing juvenile seedlings of Eucalyptus camaldulensis in the nursery for plantation purposes. The application of poultry manure significantly increased the vegetative growth of Moringa oleifera (Dania et al., 2014). Haouvang et al. (2017) stated that organic amendments in general and cow dung compost in particular could constitute the best fertilizer to improve growth of Moringa oleifera in pots. Based on the research findings, farmers can use poultry manure at an application rate of 500g per planting pot for improving the growth of Coffea arabica seedlings (Musagomba, 2017). Oroka and Ureigho (2019) recommended the use of Tithonia + poultry manure mixture for better performance of Irvingia wombolu seedlings. The increase in growth of seedlings with poultry droppings application stressed its importance during the seedling emergence of tree plants (Agboola and Adedire, 2002).
The least growth parameters recorded from seedlings planted in the soil without influence of organic fertilizer showed that there was no enough nutrient present and released by sand. Organic fertilizers released the nutrient for the growth of T. indica compared with poor fertility sand used under the control experiment. All seedlings planted in organic fertilizers performed better than those of untreated seedlings. These results are consistent with the reports of Rotowa et al. (2020) who stated that plant growth is directly related to the availability of nutrients in the soil as the Eucalyptus torelliana planted in treated soil samples performed better than those in the untreated soil. The organic fertilizer improves the organic carbon status and available NPK and S in the soil, thereby sustaining soil health and improving plant growth (Aderounmu and Olajuyigbe, 2019). This is in consonance with the reports of Musagomba, (2017) who documented that at all application levels, all the organic fertilizers performed better than the control (untreated soil) when used for Coffea arabica.

Conclusion
To forestall the threat of extinction of our indigenous economic tree species like T. indica, adequate nutrition with the use of natural, safe, affordable and environmentally friendly fertilizer is essential, for successful growth of the seedlings to meet population demand and ensure biodiversity conservation. Investigation on the influence of organic fertilizer on the growth of T. indica revealed that goat droppings enhance its growth better than other studied manure.
different organic manure at the early stage. European Journal of Agriculture and Forestry Research, 8(3), 17-26.