The study was conducted for two seasons (August to December 2017 and March to July 2018) at the National Crops Resources Research Institute (NaCRRI), Namulonge, Wakiso district in Uganda. The station is located between 0˚32'' and 32˚37'' North and East at an elevation of 1150 m above sea level. It experiences a bimodal rainfall pattern with an average rainfall of 1270 mm. The minimum and maximum temperatures of 15.9˚C and 28.4˚C with Ferrallisol soils covered with tall grassland vegetation.

Prior to the start of the experiment, soils from the study site where tested in the laboratory to ascertain their nutrient compositions. Four soil samples were randomly taken (0.0 - 15 cm) from the experimental site. The samples were properly mixed to make one composite sample which was taken to the laboratory for routine analysis. Routine analysis was done by the soil and plant analytical laboratory of Makerere University following procedures described by Carter [12]. Organic matter (O.M) was determined by Walkley-Black dichromate digestion method [13] and total soil nitrogen was determined by the Salicylate-hypochlorite method [14]. Available P was determined by Bray-1 method and colour was developed in soil extracts using the ascorbic and acid blue colour method [15]. Exchangeable K, Ca and Mg were extracted using ammonium acetate. K was determined on flame photometer and Ca and Mg by EDTA titration. The soil pH in 0.01 M CaCl₂ was determined using a pH meter. The soil nutrient composition is shown in Table 1.

Tomato seeds of line MT56 were obtained from Horticulture and Oil palm program at NaCRRI. The MT56 line was selected as a test crop for the study due to

its good attributes of disease resistance and high yield [16]. A raised nursery bed of 1 × 2 m was prepared where tomato seeds were planted in a mixture of forest soil and sand mixed in a ratio of 3:1. Tomato seeds were sown at 1 - 2 cm deep and spaced 5 × 10 cm between plants and rows. The seeds were lightly covered with fine-sand and mulched with banana leaves. The nursery bed was watered twice (morning and evening) a day to ensure sufficient moisture for seed germination. The mulch was removed on germination to allow proper seedling establishment. Cypermethrin at a rate of 1.5 ml/L was used to control insect pests. Similarly, Mancozeb (80 WP) was applied at a rate of 2.5 g/L to control common fungal diseases like dumping off. The seedlings were thinned and harden to adapt to field conditions before being transplanted into the main field.

Land meant for the trial was cleared using herbicide Agrosate (Glyphosate as the active ingredient) which was applied at a rate of 10 ml/L followed by primary and secondary tillage. Harrowing was done to make a fine seed bed. The land was then marked into 3 × 3 m plots. NPK 17:7:17 fertilizers were obtained from agro-input dealers in Kampala and decomposed poultry manure was collected locally from poultry units on farms. The organo-yield biochar was acquired from organo-yield Uganda limited. To ascertain the levels of nutrients in the soil amendments, samples were taken from poultry manure and organo-yield for analysis. Previous laboratory procedures used to analyze soil was used for nutrient analysis. Nutrient analysis for NPK was not done because its nutrient content was already known from the manufacturer’s formulation.

Healthy, vigorous and uniform in size tomato seedlings were selected and transplanted from the nursery to the main field, 21 days after sowing. Transplanting was done in the evening to avoid transplanting shock. A seedling was planted per hole in a 3 × 3 m plot at a spacing of 60 × 60 cm to attain a planting density of 25 plants per plot. The seedlings were immediately watered after transplanting and all plots were mulched to conserve moisture within the soil. The experiment was laid in a Complete Randomized Block Design (CRBD) with four treatments, replicated three times. The treatments were; poultry manure, NPK 17:17:17, organo-yield fertilizer and a control. The treatments which constituted the soil amendments (poultry manure, NPK and organo-yield) were applied within the planting hole at a rate of 1.25 kg per plot.

Hand weeding was done twice, at the plant establishment stage and at flowering stage, pruning of some leaves and emerging twigs were among the managerial activities which were done during the cropping season. Mancozeb (80% WP) was sprayed at rate of 2.5g/L at an interval of two weeks to control late blight (Phytophthora infestans) and other fungal related diseases. Furthermore, scouting for pests attacks was done every after a fortnight and spraying of cypermethrin at a rate of 1.2 ml/L was done when scouting results shown pest infestation above the threshold.

During growth, 20 plants from each plot were randomly selected and tagged from which all the required data was collected. Data on plant height (cm), number of branches and leaves per plant as well as stem girth was collected from tagged plants at 20, 40 and 60 days after transplanting. Plant height was measured in centimeters using a tape measure with the zero cm end placed at the soil level and measurements taken at the tip of the plant. Number of branches per plant was the minor branches from the main stem, which were singly counted and leaves per plant were obtained by singly counting each leaf on the plant. Stem girth was measured using a small thread. The thread was placed around the stem, 2 cm above the soil level, to obtain the circumference and then transferred to a ruler to read off the measurements. Similarly, during the reproductive and maturity stages data on flower clusters and fruits was collected. The number of flower clusters per plant was obtained by counting the number of flower clusters on each plant and number of fruits for each plant per harvest was obtained by singly counting the number of fruits harvested. Fruit weight for each plant was obtained by weighing the fruits harvested per plant using a digital weighing scale. Three fruit harvests were done at one-week interval and the accumulative harvests were summed up to get the total yield. The total yield from the 20 plants was extrapolated to plot basis and finally to per hectare basis. All the data collected were subjected to analysis of variance (ANOVA) using Genstat software version 11 [17] and results were expressed as mean values. Significances of treatment means were derived using the least significant difference. On the other hand, the soil property data collected before and after cropping were compared for all treatments with critical values to determine effect of the treatments on the soil properties.

The trend of tomato height under different soil amendments was observed at 20 days interval and for all amendments including the control plant exhibited an increment in height from transplanting up to the 60^th day. However, at 20^th, 40^th and 60^th day plant height in plots applied with organo-yield, poultry manure and NPK was significantly (P < 0.05) different from the control (Table 2). Similarly, stem girth also increased from the day of transplanting up to the 60^th day. But at 20^th day stem girth in plots applied with poultry manure was significantly different from the rest of other plots applied with amendments (Table 2). On the hand at 40^th day stem girth of plants applied with soil amendments was significantly (P < 0.05) different from plants in the control plot. At 60 days, plants applied with poultry manure had significantly (P < 0.05) higher stem girth than the rest of the treatments (Table 2).

From the transplanting date, the number of tomato branches and leaves was

Plant height and stem girth means followed by different letters in a column are significantly different and means followed by a similar letter are not significantly different.

monitored and an increase in both was observed (Table 3). This was expected as the leaves and branches are expected to increase during the vegetative stage. However, at 20 and 40 DAT the number of leaves in plants applied with poultry manure and NPK were significantly (P < 0.05) higher than that of organo-yield and the control. But at 60 DAT all plants applied with different soil amendments had significantly high number of branches than the control (Table 3). On the other hand, the number of leaves also varied after transplanting, at 20 DAT plants applied with organo-yield and poultry manure had significantly high number of leaves than control and NPK. Whereas at 40 and 60 DAT all plants in soil amendment applied plots had significantly more leaves than the control

The number of fruits per tomato plant and yield where significantly (P < 0.05) influenced by season and soil amendments applied (Table 4). The number of tomato fruits per plant observed in season 2018B was two folds higher than in season 2017A. During 2017A season plots applied with poultry manure and NPK produced the highest number of tomato fruits while plots applied with organo-yield and the control produced the least number of fruits per plant (Table 4). On the other hand, in 2018A, the highest and the lowest number of tomato fruits were recorded in plots applied with organo-yield and the control respectively. However, for either season, the number of fruits observed in plots applied with poultry manure and NPK did not vary significantly. Furtherstill, a significant interaction between soil amendments and seasons were observed which indicated that the soil amendments and seasons interacted to influence number of tomato fruits produced per plant.

The results further showed that tomato yield was significantly (P < 0.05) influenced by season and soil amendments applied. Tomato yield realized in 2018A was twice higher than in 2017B (Table 4). In 2017B, plots applied with poultry manure and NPK produced equally high yield which was significantly different from yield obtained from the organo-yield and control applied plots. On the contrary, in 2018A, plots applied with organo-yield produced the highest

Number of branches and leaves followed by different letters in a column are significantly different and means followed by a similar letter are not significantly different.

Number of fruits and yield means followed by different letters in a column are significantly different and means followed by a similar letter are not significantly different.

yield followed by poultry manure, NPK and the lowest yield was obtained from the control plots (Table 4).

Before conducting the experiment, the nutrient status of soil was determined and observations were made at the end of experiment to ascertain any changes in soil properties that might have arose due to soil amendment application. The application of organo-yield and poultry manure led to greater and marginal improvement in soil pH, respectively. Similarly, application of organo-yield improved organic content above the critical level while in plots where NPK was applied no change in organic carbon was observed (Table 5). The results also indicated that application of organo-yield and poultry manure greatly and marginally reduced the bulk density at the end of the cropping season while in plots where NPK was applied the bulk density did not change (Table 5). Before application of the soil amendments nitrogen levels in the soil were below the critical levels, but application of organ-yield greatly raised the N levels above the critical level at the end of the cropping season. Also, application of organo-yield greatly improved levels of phosphorus and potassium in the soil whereas poultry

*** Great improvement; **Marginal improvement; *No improvement.

manure and NPK did not improve P and K levels above the critical levels at the end of the cropping season. Furthermore, application of NPK greatly improved calcium content though at the end of cropping season it was still below the critical level. Although at the beginning of the cropping season, there was sufficient magnesium in the soil but application of organo-yield and poultry manure marginally and greatly improved its content, respectively. However, in plots applied with NPK no improvement in magnesium content was observed. Application of poultry and organo-yield improved soil properties significantly (P < 0.05) as compared to NPK use.