Use of improved Milled composted Pine bark for growing tomato and cucumber seedlings in Zimbabwe

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1 Scholarly Journal of Agricultural Science Vol. 3(2), pp , February 2013 Available online at ISSN Scholarly-Journals Full Length Research Paper Use of improved Milled composted Pine bark for growing tomato and cucumber seedlings in Zimbabwe Matenda, T, Mtaita, T.A and Shoko M 1 Africa University, Faculty of Agriculture and Natural Resource, P.O Box 1320, Mutare, Zimbabwe 1 Great Zimbabwe University, Faculty of Agricultural Sciences, Bag 1325, Masvingo, Zimbabwe Accepted 5 May, 2012 Pine bark has to be amended in order for it to sustain seedling growth in the nursery. The experiment was carried out to evaluate potential benefits of composting milled composted pine bark with cattle manure. Mixed formulations of various manure ratios of 20% fresh manure, 30% fresh manure, 40% fresh manure and AN (34.5N%) and lime in the ratio 1:1 were composted over 112 days. Various media elements were measured after 28, 56, 84 and 112 days of composting. In the nursery Tomato (Lycopersicum esculentus), Cucumber (Cucumis sativa) and Pine (Pinus patula) were used to determine influence of substrate quality on growth of the seedlings. Significant interactions (P<0.05) were noted between composting method used and the media type used on the nutrient elements measured. There were significant interactions of substrate and composting method for cucumber and tomato seedlings of above ground dry weight, root dry weight and leaf numbers. Media containing 40% manure and that containing ammonium nitrate with lime under plastic mulch was suitable since nutrient levels which are acceptable for seedling growth during the first 56 days of composting. Composting media beyond 56 Days did not prove to benefit as it might lead to poor seedling uptake due to poor nutrient availability and high salt concentration. Key words: composting, cucumber, seedlings, manure ratios INTRODUCTION The purpose of a potting media is to satisfy the needs for good seedling growth within the limited space of a container and to prepare it for successful transplanting. The media supports a growing seedling physically and stores and supplies nutrients, water, and air to the root system. Good media allows better development of healthy seedling with strong, fibrous root system and subsequently a better quality seedling. The major aims of this work were (1) to determine chemical and physical composition of different treatments of cattle manure and milled composted pine bark and (2) to assess the growth of selected seedling species in the mixture of cattle Corresponding Author munashoko@yahoo.co.uk manure and milled composted pine bark MATERIALS AND METHODS Two experiments were carried out from at Africa University farm, in Zimbabwe In the first experiment, dairy cattle manure was composted together with milled pine bark obtained from timber sawmill waste. The organic material substrate formulations by volume were in three ratios of milled pine bark to fresh cattle manure that is, pine bark plus 20 % fresh manure, pine bark plus 30 % fresh manure and pine bark plus 40 % fresh manure. A fourth composition made comprised ammonium nitrate (34.5%N) fertilizer and lime in a 1:1 ratio. Each formulation was divided into two heaps. The formulations containing pine bark, manure, lime and

2 Scholarly J. Agric. Sci. 48 Table 1: Some chemical and physical characteristics of pine bark samples Analysis Description Chemical characteristics Pine bark conductivity (ds/m) 0.2 Pine bark ph 3.8 Available phosphorus (%) 0.27 Exchangeable potassium (me%) Exchangeable calcium (me%) 0.02 Exchangeable magnesium (me%) 0.06 Available copper (ppm) 0.29 Available zinc(ppm) 1.16 Available nitrogen (%) 0.25 Organic carbon (%) 9.35 C:N Ratio 37.1 ammonium nitrate were thoroughly mixed before decomposition. One heap was allowed to compost under open air and the other under black plastic. The substrate was composted for 16 weeks and the temperature readings were recorded once a week. Once the heaps were established, water was applied to provide moisture for decomposition. Original components (raw pine and dairy cattle manure) and samples of the substrate were taken after every four weeks for analysis. Samples were analyzed for nitrogen (N) using the colometric method, phosphorus (P) using the Mehlich-3 method, potassium (K) using the Mehlich-3 method, organic carbon (C) using the Walkley Black wet oxidation method, electrical conductivity (EC) using the conductivity meter and ph was measured in 0.01MCaCl 2. In the second experiment, the treatment in the nursery house comprised of tomato (Lycopersicum esculentus), cucumber (Cucumis sativa) and pine (Pinus patula) combined factorially with eight pine nutrient enhancement levels. The experiment had twenty-four treatments laid out in a randomized complete block design with five replications. The seeds were germinated in river sand and then pricked into the formula substrate. After 16 weeks of decomposition, 5kg of the composted media in their respective ratios were placed in polythene bags. Seedlings germinated in river sand were pricked into the media formulations. Ten polythene bags each containing two seedlings constituted an experimental unit. The total number of seedlings per experimental plot was 20. Data on plant height, collar diameter and leaf numbers were recorded at weekly intervals until seedlings reached two months of growth for tree seedlings and first flowering for herbaceous seedlings. At transplanting stage for herbaceous species, root length, shoot dry biomass and root dry biomass were recorded. In order to obtain biomass, the roots and shoots were dried in an oven at 95 C for 12 hours. The plant material was then weighed on a sensitive scale. Analysis of data was carried out using Genstat Release 3.2 statistical package. The statistical significance of the results obtained was assessed by Least Significant Difference (LSD) and Duncan s multiple range tests with a probability level of 95%. Chemical analysis treatments results were not evaluated across composting days. RESULTS Physical and chemical characteristics of media Pine bark characterization The bark contained an acidic ph of 3.8 (Table 1). Conductivity of the raw bark was below 1ds/m. The pine used contains relatively high C:N ratio of 37:1. Pine bark contains very low available nitrogen; therefore, it is essential to amend it using amendments that have high nitrogen content. The available phosphorus content in the media was 0.27, which was able to sustain bare root seedlings. Potassium levels in the media were me% which was very high. Pine bark contains very low calcium of 0.02 me% and magnesium levels of 0.06 me% and these had to be amended.. Composted pine bark ph Before composting, ph was in the range of 4.3 to 4.9 (Table 2). There was increase in the ph of the media with the addition of either manure or lime after composting. After 28 composting days, a change in the range of 3.1% to 3.5% was observed from the initial ph at zero composting days. Benefits in amending the pine and composting the media were observed by the increase in ph. There were significant interaction (P<0.05) between media type used and the composting method applied on the ph of the composted media since both composting methods after 28 days gave ph ranges that coincide with those required for seedling growth (5.0 to 6.5)(Table 3). The highest ph of the media was realized after 28 composting days. Increase in the composting days resulted in a decline in the ph; however the ph of the media started to increase after 84 composting days. The ph raise was in the range of 4.8 to 6.6 over the 112 day

3 Matend et al. 49 Table 2: media status after 0 days of composting Media Type ph EC OC AN Ph Ca K Mg 20 % manure + open air b b 1.76 ab 0.68 a 0.96 cd 4.15 b 0.11 c 30 % manure + open air b e 1.52 cd 0.75 a 0.75 f 3.95 b 0.14 bc 40 % manure + open air b f 1.34 e 0.62 a 1.07 ab 4.12 b 0.16 bc AN + lime + open air a d 1.29 e 0.56 a 0.92 de 6.86 a 0.25 a 20 % manure + under plastic b c 1.88 a 0.58 a 1.10 a 4.02 b 0.12 c 30 % manure + under plastic b d 1.67 bc 0.61 a 0.89 e 4.08 b 0.13 c 40 % manure + under plastic b d 1.21 e 1.02 bc 4.25 b 0.19 abc 0.19 abc AN + lime + under plastic a a 1.36 de 0.45 b 1.06 ab 5.99 a 0.22 ab Mean P Value NS * * * * * * * LSD CV% Within the columns means with at least a common superscript are not significantly different using the LSD Ns denotes non significance at P=0.05. Table 3: Media status after 28 days of composting Media Type ph EC OC AN Ph Ca K Mg 20 % manure + open air c a 1.40 a 0.07 d 0.20 a 3.15 c 0.15 ab 30 % manure + open air b d 1.02 c 0.57 a 0.03 b 3.08 c 0.08 bc 40 % manure + open air b c 0.96 c 0.38 bc 0.05 b 3.64 bc 0.12 abc AN + lime + open air a c 1.11 b 0.43 b 0.04 b 5.00 ab 0.13 abc 20 % manure + under plastic c 7.93 f 1.20 b 0.10 d 0.17 a 3.97 abc 0.06 c 30 % manure + under plastic b b 1.02 c 0.31 c 0.02 a 3.85 bc 0.08 bc 40 % manure + under plastic a c 1.10 bc 0.54 a 0.04 a 2.87 c 0.13 abc AN + lime + under plastic a e 1.10 bc 0.53 a 0.06 a 5.12 a 0.18 a Mean P Value NS * * * * * * * LSD CV% Within the columns means with at least a common superscript are not significantly different using the LSD Ns denotes non significance at P=0.05. composting period (Table 6). All the media recorded a decrease in ph at 56 days of composting with the exception of 30 % manure under plastic cover (Table 4). Decreases were in the range of 4.3 % to 4.8 %. Compost containing 20 % manure and 40 % manure composted in the open air had ph greater than 6 after 112 composting days (Table 6). Organic carbon There was significant interaction (P<0.05) between composting method and manure levels on the organic carbon content of the media. There were significant changes in organic carbon percentage over time. There was a significant difference (P<0.05) in the composting days on organic carbon. Addition of either manure or inorganic fertilizer and lime lead to an increase in organic carbon content 28 days after composting as compared to the amount of organic carbon in unamend pine bark except with composting using lime and ammonium nitrate under plastic (Table 3). Significant difference (P<0.05) were noted in the media formulations that were composted. There were significant interactions (P<0.05) between composting method and nutrient levels, and between composting days and composting method on organic carbon. Significant differences (P<0.05) amongst composting method, composting days and manure levels were noted. At 28 composting days, open air composting had a higher organic carbon content value over composting under plastic (Fig. 1). At 56 composting days there was no difference in organic carbon content amongst the composting methods. After 56 and 112 days, composting under plastic yielded greater mean organic carbon content values over composting in the open environment (Fig. 1). Over time, composting under plastic cover resulted in an increase in the amount of organic carbon available in the media. Available nitrogen Significant interaction (P<0.05) between composting days, composting method and nutrient level were noted.

4 Mean organic carbon content (%) Scholarly J. Agric. Sci open air composting plastic composting Days of composting Figure. 1. Effect of composting method on organic carbon content of pine media Table 4: Media status after 56 days of composting Media Type ph EC OC AN Ph Ca K Mg 20 % manure + open air b c 1.34 a 0.08 e 1.47 b 6.85 b 0.08 b 30 % manure + open air b e 1.03 c 0.57 a 0.07 g 8.83 a 0.09 b 40 % manure + open air a f 1.14 bc 0.43 bc 0.78 e 6.59 b 0.20 a AN + lime + open air a f 1.14 bc 0.43 bc 0.78 e 6.59 b 0.20 a 20 % manure + under plastic b 9.24 g 1.28 ab 0.12 e 0.67 f 5.80 b 0.07 b 30 % manure + under plastic b a 1.03 c 0.31 d 0.02 g 6.16 b 0.11 ab 40 % manure + under plastic a b 1.15 bc 0.50 ab 1.10 d 6.39 b 0.13 ab AN + lime + under plastic ab d 1.34 a 0.51 a 1.30 c 7.18 b 0.15 ab Mean P Value NS * * * * * * * LSD CV% Within the columns means with at least a common superscript are not significantly different using the LSD Ns denotes non significance at P=0.05. There was an increase in the available nitrogen in the decomposed bark after addition of either inorganic fertilizer and lime or dairy manure from the initial unamended pine bark. Increases in available nitrogen were noted 56 days after composting ranging from 2.06% to 16.14% with the exception of inorganic fertilizer and lime composted in the open air where a decline of 0.9% was observed (Table 4). Decline in available nitrogen was observed after 84 days with the exception of media containing 20 % and 40 % manure composted in the open environment (Table 5). Increases in available nitrogen were noted after 112 composting days with the exception of pine composted with 30 % manure in the open environment and the one containing 40 % manure composted under plastic (Table 6). Composting the media containing 20 % manure in the open air for 28 or 56 days gave a nitrogen range recommended by Landis (2005) for bare root seedling growth. Composting containing ammonium nitrate and lime obtained acceptable levels at 56 composting days (Table 4) while that containing 20 % manure under plastic at 112 days (Table 6). The amount of nitrogen made available at 20 % manure was greater than that at 40 %. C: N Ratio There was a decrease in the C: N ratio of the amended pine bark mixtures when compared with raw pine bark. The C: N ratio decreased from 37:1 (Table 1) to a range of 6:1 to 23:1 (Fig. 2). Compost composted under plastic resulted in a significantly lower C: N ratios compared to compost composted in the open air. There was a decrease in C: N ratio from 20 to 15 with increases in manure content in the composts during the first 28 days of composting (Fig. 2). After 112 days of composting, C:N ratios of the media were in the ranges of 6:1 for media containing 20% manure composted in the open air and

5 Matend et al. 51 Table 5: Media status after 84 days of composting Media Type ph EC OC AN Ph Ca K Mg 20 % manure + open air b 9.05 e 1.26 a 0.10 g 1.23 d 7.04 c 0.08 cd 30 % manure + open air b 7.13 f 1.02 b 0.58 a 0.66 f 9.63 b 0.11 cd 40 % manure + open air a d 1.28 a 0.49 bc 1.70 a 7.21 c 0.14 abcd AN + lime + open air a c 1.22 a 0.42 cd 1.03 e 3.92 d 0.18 ab 20 % manure + under plastic b a 1.27 a 0.21 f 1.52 b 4.25 d 0.05 d 30 % manure + under plastic b b 1.01 b 0.36 e 0.31 g a 0.22 a 40 % manure + under plastic b d 1.17 ab 0.41 de 1.44 c 6.65 c 0.14 abcd AN + lime + under plastic b c 1.02 b 0.55 a 1.75 a 7.01 c 0.15 abc Mean P Value NS * * * * * * * LSD CV% Within the columns means with at least a common superscript are not significantly different using the LSD Ns denotes non significance at P=0.05. Table 6: Media status after 112 days of composting Media Type ph EC OC AN Ph Ca K Mg 20 % manure + open air a b 1.16 bc 0.12 f 1.33 e 1.85 e 0.08 bc 30 % manure + open air b 6.76 f 1.04 c 0.56 a 0.53 d b 0.13 abc 40 % manure + open air a e 1.25 b 0.50 ab 1.52 d 8.94 c 0.19 a AN + lime + open air a e 1.15 bc 0.41 cd 1.34 e 5.11 d 0.17 ab 20 % manure + under plastic b a 1.41 a 0.27 e 1.66 c 8.26 c 0.05 c 30 % manure + under plastic a c 1.13 bc 0.34 de 0.63 c a 0.10 abc 40 % manure + under plastic a c 1.20 bc 0.44 bc 1.90 a 8.29 c 0.15 ab AN + lime + under plastic a d 1.28 b 0.55 a 1.76 b 9.04 bc 0.16 ab Mean P Value NS * * * * * * * LSD CV% Within the columns means with at least a common superscript are not significantly different using the LSD Ns denotes non significance at P=0.05. media containing ammonium nitrate and lime composted under plastic mulch to 13: 1 for media containing 20% manure composted under plastic mulch (Fig. 2). Phosphorus There were significant interaction (P<0.05) between composting method and media type. Increase in the amount of available phosphorus were noted after 28 composting days with the exception of pine composted with inorganic fertilizer and lime as compared with the unammended pine bark (Table 3). The amount of P in the media increased with increased percentage of manure. Further increases were noted 56 days after composting with the exception of pine composted with 30 % manure under plastic. Increases were in the range of 1.8% to 28.6% (Table 4). There was a decline in available phosphorus 112 days after composting with the exception of composted using inorganic fertilizers and lime and pine composted with 40 % manure either under open environment or plastic where increases were observed (Table 6). Compost containing 20 % manure composted in the open air could not meet the recommended phosphorus range. Composting 20 % manure under plastic gave favorable results when composting had been carried out for 84 days (Table 4). All the other media composts gave favorable results suitable for seedling growth after 28 composting days. Calcium Significant interactions (P<0.05) were noted between composting method used and the media type used. There was an increase in the exchangeable calcium with the addition of either manure or inorganic fertilizer and lime. Increases were observed up to 112 composting days. During the first 28 composting days, all the media composts could not meet the recommended range of calcium levels for seedling growth, which is 0.3 to 1.0meq % (Table 3). Composting the media for 56 days gave

6 Scholarly J. Agric. Sci. 52 Figure. 1. Changes in C:N ratio over composting period Figure 3: Responses of cucumber seedling leaf number count in pine media adequate calcium to the media with the exception of 30 % manure composted in the open air. These increases

7 Matend et al. 53 were however not significant (Table 4). Potassium There were significant interactions (P<0.05) between composting method and nutrient levels, and between composting days and composting method on exchangeable potassium. After 28 composting days there was an increase in the amount of exchangeable potassium in the media (Table 3). Composting the media for 28 days would ensure adequate potassium levels for bare root seedling growth (Table 3). Magnesium Significant interactions (P<0.05) were noted between composting method and nutrient levels, and between composting days and composting method on magnesium. There were significant interactions (P<0.05) between composting days and nutrient levels on magnesium. There was an increase in the magnesium content with increase in manure content during composting increase in the amount of available magnesium were noted after 28 composting days (Table 3). Above ground dry weight There was a significant difference (P<0.05) in above ground mean dry weight of cucumber seedlings among the media types (Table 7). Significant differences (P<0.05) were noted between composting in the open air and composting under plastic cover. Media from composting under cover yielded a higher above ground biomass for cucumber seedlings as compared to those composted in the open air. Media containing 30 % manure and 40 % manure showed significant differences when composted in the open air whilst media containing 20 % manure and 40 % manure showed significant differences when composted under plastic cover (Table 7). There were significant differences (P<0.05) in media composted in the open air for above ground shoot biomass of tomato seedlings. Significant differences were however noted for media composted under plastic cover. However no significant mean differences (P>0.05) were noted between the media containing 20 % manure and 30 % manure composted under plastic though Fig. 3 indicates that tomato seedling above ground biomass was greater at 40% manure. There were significant differences (P<0.05) between the media composted in the open air. Compost containing ammonium nitrate and lime gave the highest above ground biomass for pine seedlings. There were no significant differences (P>0.05) between the media composted under plastic cover. Media containing 30% manure composted in the open air gave the least mean above ground dry weight of pine seedlings. Leaf numbers There were significant differences (P<0.05) among the media composted in the open air and media composted under plastic cover. Composting under plastic cover yielded higher cucumber leaf numbers. Significant differences (P<0.05) were noted amongst the media types. Media containing 30 % manure, 40 % manure, ammonium nitrate and lime gave no significant differences when composted in the open air. Interaction of composting method and media type gave significant differences (P<0.05) on cucumber leaf numbers. There was an increase in leaf number count with increase in the number of days indicating that cucumber seedlings were able to grow in the different media formulations. Differences in cucumber leaf number count were observed 7 days after pricking. Media 30 % manure composted under plastic and 40 % manure composted under plastic gave similar leaf number count which was the highest as compared to the other media (Fig. 3). The lowest leaf number count was observed in media 20 % manure under open air. Benefits in terms of increased leaf number count were observed in media composted under plastic. Nutrient levels for media composted under plastic cover recorded significant differences (P<0.05). Media containing 40 % manure and ammonium nitrate and lime gave no significant differences (P<0.05) when composted under plastic cover. Tomato seedlings grown in media 40 % manure composted under plastic gave the highest growth response whilst media 30 % manure composted under plastic gave the lowest tomato seedling growth response. As shown in Fig. 4, there was an increase in tomato leaf numbers with increase in the number of days indicating that the tomato seedlings were able to grow in the different media formulations. Response in growth varied with the type of media used. Differences of media response in terms of leaf numbers were observed 7 days after pricking over a 28 day growth period (Fig 4). The greatest increase in leaf number was observed between 14 and 21 days after pricking of the germinated seedlings (Fig 4). Plant height Composting in the open air and composting under plastic cover gave significant differences (P<0.05) on plant height of cucumber seedlings. Composting under plastic cover gave a higher mean plant height compared to composting in the open air. However no significant differences (P=0.05) between media containing 20 %, 30 % and 40 % manure composted under plastic cover. Cucumber seedlings grown in media 30 % manure under open air gave the highest growth response (99.8 cm). Cucumber seedlings grown in media 30 % manure under open air gave 4 times more plant height than 20 % manure under open air (Table 7). Significant interactions

8 Tomato leaf number (count) Scholarly J. Agric. Sci days 7 days 14 days 21 days 28 days % manure + open air 30% manure + open air 40% manure + open air AN + lime + open air 20% manure + under plastic 30% manure + under plastic 40% manure + under plastic An + lime + under plastic Media type Figure. 4: Responses of tomato seedling leaf numbers to pine media (P<0.05) between composting method and media type were noted on cucumber plant height. Fig. 5 shows the plant height growth response of cucumber seedlings in the various pine bark media formulations over a 28 day growth period following pricking of the seedlings. No significant differences (P>0.05) in media type and composting type for tomato plant height were observed. However, there was an increase in plant height with increase in growth duration of the tomato seedlings in all media formulations. Composting in the open air gave higher mean plant height over composting under plastic. Composting media under plastic containing 30 % manure proved to give lower response in plant height (20.6 cm) over composting 30 % manure in the open air (32 cm). There were no significant interactions (P>0.05) on tomato plant height between composting method and media type. Collar diameter Significant differences were noted amongst the nutrient levels (P<0.05) on media composted under plastic cover and that composted in the open air. There were no significant differences (P=0.05) amongst nutrient levels 20 % manure, 30 % manure, ammonium nitrate and lime composted under plastic (Table 7). Formulation 30 % manure composted in open air had the highest mean collar diameter for cucumber seedlings (8.9mm) whilst formulation 20 % manure under open air had the lowest mean (1.2mm) for cucumber seedlings. Cucumber seedlings grown in the 20 % manure composted under plastic produced 5 times more collar diameter than 20 % manure under open air. Composting methods used did not record any significant differences (P>0.05), however differences (P<0.05) were observed among the media types. Formulation 40 % manure under plastic cover had the highest mean collar diameter (7.1mm) and formulation 30 % manure composted in open air had the lowest mean collar diameter for tomato seedlings (2.4 mm). Fig 5 shows that seedlings grown in 20 % manure composted in open air produced 2.43 times more collar diameter than 20 % manure under plastic cover. DISCUSSION Chemical characteristics The chemical properties of pine bark media differ from those of mineral soils. These differences influence the amount of lime and fertilizer required for optimum growth.

9 Matend et al. 55 Figure. 5: Tomato seedling mean collar diameter in eight growing substrates Table 7: Means of collar diameter of cucumber seedlings in eight growing substrates (mm) Treatment Media Type Open air Under plastic Mean P Value 20 % manure 1.2 c 6.0 b 3.6 ns 30 % manure 8.9 a 6.0 b 7.5 ns 40 % manure 6.4 b 8.1 a 7.3 ns AN + Lime 7.2 ab 4.2 b 5.7 ns Mean P Value NS * LSD CV% Within the columns means with at least a common superscript are not significantly different using the LSD Ns denotes non significance at P=0.05. * denotes significance at P<0.001 An amendment using lime or organic residue to raise the ph of the bark to acceptable levels of 5.0 to 6.5 essential to ensure availability of phosphorus to the plant. The dairy manure used had a C:N ratio of 6.1. According to Hansel and Mancl, (1988) when the C: N ratio is 25:1 or lower; nitrogen is converted to ammonia and is released into the atmosphere as an undesirable odor. Available nitrogen observed in the dairy cattle manure used was less than that observed in cattle manure from working or older animals. According to Allison (1973), milk producing cows excrete less nitrogen than working or old animals because of their more efficient use of protein (Allison, 1973). Dairy cows also reduce the amount of dry matter since they drink lots of water thus the organic matter content recorded in the dairy cattle manure used was low. The manure contains low levels of available phosphorus which could have been as a result of the nutrient status of the feed that the cattle were fed on. Composting the media with amendments increased the ph to acceptable for seedling growth that is, 5.0 to 6.5. The ph range, which promotes micronutrient availability, is in the range 5.2. to 9.0 For the cattle manure composts, the initial fall in ph observed at 56 days of composting could be due to the production of organic acids during the early stages of composting (Gray et al. 1971) whereas the rise observed at 84 days of composting most likely reflects microbial decomposition of the organic acids, cited by Kirchmann and Widen (1994) and the release of alkali and alkali earth metals previously bound in the organic matter (Smith and

10 Scholarly J. Agric. Sci. 56 Hughes 2002). The increase in ph of pine bark-cattle manure composts observed after 28 days of composting could also have been due to the ammonification process as organic matter degraded (Sanchez - Monedero et al. 2001). The ammonia produced increases the ph during the thermophilic stages of composting. The decline in ph after the initial rise can be attributed to the nitrification process, which is always accompanied by the liberation of hydrogen ions. Compost containing ammonium nitrate composted for 28, 56 and 84 days in the open air, ammonium nitrate and lime composted under plastic cover for 28 days and composts containing 40 % manure composted under plastic for 28 and 56 days gave electrical conductivity of more than 1 ds/m (table 4.5). According to Lang (1996), the acceptable conductivity value for seedling growth recorded was 1-2dS/m. The increase in the electrical conductivity in the pine barkcattle manure mixture has been attributed to the mineralization of organic matter during composting which results in the release of bases and other nutrients that increase the EC values of the composting mixtures (Bertran et al. 2004). Mineralization of nitrogen by microbes resulted in the increase in C:N ratio (Fig. 4.2). A significant amount of carbon is lost through respiration of microbes as CO 2. Organic carbon is essential in providing decomposing microbes with carbon this results in the lowering of the C:N ratio in the media. Increases realized at 112 days can be attributed to the immobilization process taking place during composting. The amount of nitrogen made available at 20 % manure is greater than that at 40 % because the amount of microbes acting on the compost containing 20 % manure have a less nitrogen available for immobilization as compared to those in 40 % manure. The process of immobilization takes a longer time to be completed in the media containing greater nitrogen content therefore the media containing 40 % manure has less available nitrogen as compared to 20 % manure. Decline in available nitrogen observed after 84 days of composting could be due to the nitrogen being immobilized during decomposition by the microbes. Contrary to Murwira and Kirchmannn (1993) who showed that 46% mineralization occurs after third season of manure application, less than 10% of manure nitrogen was mineralized in laboratory incubations of 5 months or less. Composts containing ammonium nitrate and lime proved to contain available nitrogen ranging from 1.02 to 1.34 over the composing period. Rates of N mineralization have been found to increase by liming. Liming could thus be a means of hastening N release when it is limiting given that the unammended pine bark contained 0.25% N. The decomposition rate of manure is known to be affected by its C:N ratio. The results for C:N ratio recorded were in compliance with Swift et.al., (1979) who hypothesized that net mineralization occurs at C:N ratio of less than 23:1. According to Chen McConnell (2002), the recommended C:N ratio for foliage plants should be less than 25:1 which was achieved by the composts after 28 days of composting. The amount of available nitrogen fell below those recommended by Landis (2005) and this can be as a result of the manure used was of poor quality. Poor quality manure has reduced nitrogen content. The decline in available phosphorus in pine composted with inorganic fertilizer and lime can be attributed to fixation of phosphorus with increase in phosphorus. Composts containing 20% manure had the lowest phosphorus levels. According to Landis (2005) the recommended phosphorus levels to sustain bare root seedling growth is 0.2 to 0.6 %. A high level of calcium is undesirable because it raises soil ph and CEC and tends to promote pathogenic fungi. Addition of lime was justifiable to lower down ph of pine bark which initially was below 5 and calcium level which was less than 3.0 meq% before amendment. Since potassium is not fixed by the media and cannot be volatilized, an increase in potassium levels was recorded. Optimal potassium levels for bare root seedling growth are in the range of 100 to 200ppm. Growth characteristics Pine root dry weight did not indicate significant differences between substrates. Guerrero et.al., (2002) observed that pine grown in pine bark substrate with or without amendment, compost addition was slower than the growth observed for other ornamental plants such as Cupresuss arizonica. All physiological processes as well as morphological ones are influenced by mineral nutrition. Evaluating the effects of individual nutrients on certain aspects of seedling physiology is difficult because of the possible interaction of those particular nutrients with other aspects of seedling physiology. Mahmoud et. al., (2009) confirmed that the application of compost increased accumulation of organic C, N and phosphorous more than application of N mineral fertilizers. Vegetables grown with media with highest C:N had least value of leaf numbers and above ground biomass. This is because it would have been most resistant to decomposition and caused microbial immobilization of nutrients especially N leading to depressed plant growth (Olayinka, A., 1990). These observations indicate the importance of availability of N, P and K in determining vegetable performance (Saxena, et. al., 1975). Enhancement of vegetable performance and nutrient status by amendment of agro industrial wastes with animal manures is because the applications of sole and amended plant residues, manures have lower C: N values compared with crop wastes (Moyin Jesu, 2003). For example, Moyin Jesu (2003) recorded C:N. values of 6.9 and 7.9 for poultry and goat droppings respectively. Above ground dry weight, leaf numbers and plant height of tomato and cucumber seedlings responded in relation to the amount of nutrients that were in the media.

11 Matend et al. 57 Nitrogen, phosphorus and potassium are the macronutrients that affect growth. Media containing 20% manure and 40% manure composted under plastic had high nitrogen levels needed to produce cucumber seedlings with high above ground dry weight. Tomato seedlings in composts containing 40% manure under plastic cover had highest mean above ground dry weight. Composts containing 30% and 40% manure composted under plastic gave high leaf number count for cucumber seedlings. This implies that pine bark manure composts are inherently more fertile at 40% than pine bark composts with lime and inorganic fertilizers. It is assumed that more N was released into the media due to continuation of decomposition even after maturity. The combined effects of medium and fertilizer level in the pine bark manure compost media on above ground biomass of the vegetable transplants was the tendency to produce rank growth. Animal manures were richer in N and P. The higher nutrient status and lower C: N ratio of animal manures increases decomposition and nutrient of agricultural wastes for the growth of vegetable leaf numbers and above ground dry biomass CONCLUSION Composting the pine bark using either dairy manure or lime and ammonium nitrate facilitates the growth of germinated seedlings in the composted media. Differences noted in the growth parameters are an indicator that the media had varied nutritional status available for plant growth. Media containing 40% manure composted under plastic proved to contain nutritional elements within acceptable range for seedling growth. REFERENCES Allison, FE (1973). Soil organic matter and its role in crop production. Elseiver Scientific Publishing Company. Armsterdam Bertran, E, Sort, X, Soliva, M, Trillas, I (2004). Composting winery waste: sludges and grape stalks. Biores. Technol, 95: Gray, AL, Bush, EW, Edling, RI (1998). Cyclic irrigation effects on container grown 'Little Gem' magnolia growth and fertilizer leaching. Proc. SNA Res. Conf., 43: Guerrero, F, Gasco, JM, Hernandez Apaolaza, L (2002). Use of pine barks ad swage sludge compost as components of substrate for Pinus pinea and Cupressus arizonica. J. Plant Nutri., 25(1): Hansen, R, Mmancl, K (1988). Modern Composting. A way to recycle waste. Extension Bulletin 792. Ohio State University Kirchmann, H, Widen, P (1994). Separately collected organic household wastes: Chemical composition and composting characteristics. Swedish. J. Agric. Res., 24: Lang, HJ (1996). Growing media testing and interpretation, In: D.W. Reed (ed.) Water, media, and nutrition for greenhouse crops. Ball Publishing, Batavia, Ill. pp Moyin JEI (2003). Effects of sole and ammended agricultural byproducts on soil fertility and growth and chemical composition of budded rubber. Trop..Agric. Sci.,. 27(2):91-99 Olayinka, A (1990). Effects of poultry manure, corn straw and sawdust on plant growth and Soil chemical properties Ife. J. Agric., 12: Sanchez-Monedero, MA, Roig, A, Paredes, C, Bernai, MP (2001). Nitrogen transformation during organic waste composting by the Rutgers system and its effects on ph, EC and maturity of the composting mixtures. Biores., Technol., 78: Saxena, GK, Locascio, SJ, Lucas, JB (1975). Effect of N.P and K rates on response of cabbage and tomato grown on a coastal clay soil of Guyana. Trop. Agric., 52: Smith, DC,.Hughes, JC (2002). Changes in chemical properties and temperature during the degradation of organic wastes subjected to simple composting protocols suitable for small scale farming and the quality of the mature compost. S. Afr. J. Plant Soil, 19: