THE SOIL MOISTURE RETENTION PATTERN OF SOME SELECTED OF ORGANIC MEDIA UNDER A GREENHOUSE STRUCTURE

This research aimed to investigate the soil moisture retention of some selected organic media for growing cucumber plant. The experiment was conducted in a greenhouse structure and moisture content of each of the organic media was determined by a calibrated moisture meter, which was taken before and after the irrigation. The water application was uniform, using a drip irrigation kit for potted system with a capacity of 75cl storage each for the treatments. The pH values of each of the organic media used shows moderate alkalinity. The mean and sample variance of the moisture retention pattern for each of the media gave; saw dust (3.61, 0.073), maize husk (3.41, 0.044), rice husk (3.92, 0.034), eucalyptus leaves (3.27, 0.021), sawdust + soil (2.76, 0.0416), maize husk + soil (2.94, 0.153), rice husk + soil (3.88, 0.069), eucalyptus leaves + soil (2.76, 0.041), eucalyptus leaves + soil unsterilized (3.77, 0.074), and sandy loamy (23.345, 0.009). Moisture retention pattern of the selected media show high moisture retention in sandy loam while other media show a low moisture retention in approximately ratio 6:1, the sample variance shows small variance indicating how the data point spread out. It can be assumed that low retention could be as a result of the presence of fibre or coarse particles given room for large pore spaces that allows easy moisture drain from the organic media. It can also be deduced from the results that maize husk is least suitable for growing purposes because of unsteady moisture retention pattern.


INTRODUCTION
Growing media have some roles such as providing aeration and water, permitting maximum root growth and supporting physically the plant. There are many differed materials that have been used for vegetable production. Throughout the world, the raw material used were based on their local availability (Sclimilewski, 2009). Such raw material can be inorganic or organic, but growing media are often formulated from a blend of different raw materials in order to achieve the correct balance of air and water holding capacity for plants to be grown as well as for the long term stability of the medium (Bilder Back et al., 2005;Nair et al., 2011). It is reported that a high percentage of inorganic growing media such as rock wool, sand per litter, vermiculite, pumice, clays, and other, are used in soils plant production, while only about 12 % uses organic growing media such as peat, bark, wood residues. (Leaf mould, saw dust, barks). Coir, bagasse, rice hulls and other (Bonnan, 1998). Accurate information of moisture retention of organic media would help to know how much moisture that can be retained in the media at a particular growing period and help to know how to schedule effective irrigation operation for maximum crop production.

METHODOLOGY Description of the Experimental Site
The study was carried out at the experimental field of the Federal College of Forestry Mechanization, Afaka Igabi Local Government of Kaduna State, Nigeria. The experimental farm is located at latitude 10 0 37′ N and longitude 7 0 47′ E, and situated in the Northern guinea savannah ecological zone of Nigeria. The experiment was conducted inside a control environment structure so as to avoid rainfall interference during the period of the experiment. Plate 1 showed the front and side view of the greenhouse structure used for this experiment and the isometric projection of the structure (Figure 1).

Experiment Design and Layout
The experiment for moisture retention was carried out in a greenhouse structure for a period of 56 days. A gravity flow drip irrigation kit for potted plant as shown in (Plate 2) with the capacity of 75 cl storage which after each irrigation is refilled. The growing media were sawdust, rice husk, maize husk, eucalyptus leaves, sawdust mixed with sandy-loamy soil, rice husk mixed with sandy-loamy soil, maize husk mixed with sandy-loamy soil, eucalyptus leaves mixed with sandy-loamy soil, and sandy-loamy soil as the control of equal volume (4000 cm 3 ). The moisture content of each medium was measured before irrigation and one hour after irrigation, so as to determine the moisture retention capacity for each growing medium. The experimental layout was designed using the Randomized Complete Block Design ( Figure 2) and Table 1 shows that The field experiment also consists of eleven (11) treatments which was replicated three times. The experiment was carried out in March to April, 2019. The water was applied using irrigation kits, with 75 cl per volume of water applied once in 2 days.  TI  T4  T7   T2  T1  T9   T3  T10  T2   T4  T5  T10   T5  T9  T1   T6  T11  T9   T7  T2  T11   T8  T5  T3   T9  T7  T6   T10  T8  T4   T11  T6  T8   THE

Moisture Content Determination
The media was crushed and equal volume of moisture was added to each of the organic medium. After which a moisture meter was used to determine the moisture content. The same media moisture content was also determined using gravimetric method. A linear regression analysis was carried out on both the values obtained from moisture meter and gravimetric method to generate the calibration equation (Table 2)  Rice husk and eucalyptus leaves shows a steady increasing pattern of moisture retention, while sawdust and maize husk shows unsteady pattern of moisture retention as shown in figure 3. Figure 3: The graph of moisture retention against DAP for growing media; sawdust, maize husk, rice husk and eucalyptus leaves.

Moisture Retention Pattern for Sawdust + soil, Maize husk + soil, Rice husk + soil, Eucalyptus leaves + soil and Eucalyptus leaves + soil unsterilized
The rice husk + soil and Eucalyptus + soil unsterilized shows a slightly higher moisture retention at approximately 4% while others shows approximately the same values 3% (Sawdust + soil, Maize husk + soil and Eucalyptus leaves + soil). The standard deviation shows how their values deviate from the mean showing low values for all the media in this category. Eucalyptus leaves + soil shows the lowest sample variance indicating how well the moisture content was spread out within the medium, as all the details of the data obtained relating to this category of moisture retention is shown in Table 4.   Figure 4. Figure 4: The graph of moisture retention against DAP for growing media; Sawdust + soil, Maize husk + soil, Rice husk + soil, Eucalyptus leaves + soil and Eucalyptus leaves + soil unsterilized.

Moisture Retention Pattern for Sandy Loamy Soil
The average moisture for the duration of the experiment was 23.34% which was higher than what was obtained from other organic media and it shows the lowest sample indicating how the moisture was spread within the soil, the details of this is shown in Table 5. The soil shows a steady pattern of moisture retention as shown graphically in figure 5.

DISCUSSION
In general, the organic media used in this experiment shows a low moisture retention capacity as compared to the soil used about ratio 1:6 approximately. The reason for this can be deduced from the fact that the organic media having coarse substances as part of the mixture thereby increasing pore spaces with the media, aiding easy drain of moisture from the media.

CONCLUSIONS
The moisture retention pattern of the selected media was obtained and some media shows steady pattern of moisture retention while some doesn't show unsteady moisture retention pattern. It can be inferred that the organic media that shows steady pattern of moisture content retention can be used for organic planting purposes as this would not be complicated for planning irrigation scheduling and not to have the plant grown on it to be stressed at any period of its growing season. So, from this study Maize husk and maize husk + soil doesn't exhibit a good organic medium for plant growth as it gave unsteady pattern of it retention since all these growing media was subjected to the same condition.