## Study The Thermal Properties of The Soil Under Systems Irrigation and Mulching Different | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

Al-Qadisiyah Journal For Agriculture Sciences | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

Article 12, Volume 10, Issue 2, Autumn 2020, Page 415-425
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DOI: 10.33794/qjas.2020.167503 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

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Athmar Jameel Kareem Al-Lame^{*} ; Jamal N. A. Al-Saadoon | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

^{}College of Agriculture, University of Wasit, Iraq | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

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A field experiment was carried out in the field of the Faculty of Agriculture / University of Wasit located at a longitude 45° 50' 33.5"east and N 29° 36' 49.8" norths for the 2019 growing season, with the aim of studying thermal properties under different irrigation and mulching systems. The study was carried as factorial experiment in RCBD design with three replications, the first factor was mulching (control, wheat straw, palm fronds, and black nylon), and the second factor was irrigation methods (basin, and furrow). Maize crop was planted on 20/7/2019, and harvesting was completed on November 20, 2019. The thermal properties were estimated using equations (thermal conductivity, heat flow, volumetric heat capacity, thermal diffusion), the results showed the following: It is noticed that superiority of the treatment of mulching with black nylon at the beginning and end of the season by obtaining the highest thermal conductivity of the soil, followed by the treatment of straw and fronds compared to the treatment without mulching, as it reached at the beginning of the season 0.830, 0.769, and 0.752 W∙m ^{−1}∙K respectively, and reached at the end of the season 0.772, 0.813, and 0.834 W∙m^{−1}∙K respectively, while the thermal conductivity of the control was 0.665, 0.746 W∙m^{−1}∙K at the beginning and end of the season respectively.The basin irrigation method outperformed the furrow irrigation method in the thermal conductivity values at the beginning and the end of the season, reaching 0.733 and 0.775 W∙m ^{−1}∙K respectively at the beginning of the season and 0.785 and 0.797 W∙m^{−1}∙K respectively at the end of the season.The black nylon mulch treatment outperformed the rest of the treatments at the beginning of the season, followed by the non-mulched treatment, then the frond mulching and straw mulching treatment by obtaining the highest heat flux rate of 2.96, 3.30, 4.47 and 6.80 W/m ^{2}, respectively.The basin irrigation method outperformed the furrow irrigation method by obtaining the highest heat flux at the beginning of the season, reaching 5.99, and 2.77 W/m ^{2}, respectively, but the opposite happened at the end of the season where the furrow irrigation method outperformed the basin irrigation method, reaching 3.99, and 3.85 W/ m^{2} respectively.The mulching treatment with black nylon exceeded by obtaining the highest values of volumetric heat capacity, then followed by the treatment of mulching with straw and fronds, and then treatment without mulching at the beginning and end of the growing season, reaching 1.61, 1.53, 1.49, and 1.39 MJ / m ^{3} respectively at the beginning of the season and 1.52, 1.54, 1.54 and 1.63 respectively at the end of the season.The basin irrigation method outperformed the furrow irrigation method in that it obtained the highest values of volumetric heat capacity which were 1.48 and 1.53 MJ / m ^{3}.K respectively at the beginning of the season and 1.57 and 1.54 MJ / m^{3}.K respectively at the end of the season.The treatment of mulching with black nylon outperformed by obtaining the highest value of thermal diffusivity, followed by the treatment of mulching with fronds and straw, compared to a treatment without mulching at the beginning of the season, which amounted to 5.18x10 ^{-7}, 5.06x10^{-7}, 5.01x10^{-7}, and 4.79x10^{-7} m^{2} / sec respectively.The basin irrigation method achieved the highest rate of thermal diffusivity compared with the furrow irrigation method at the beginning of the growing season, reaching 5.09 x10 ^{-7}, and 4.94x10^{-7} m^{2} / sec respectively. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

Keywords | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

thermal properties; systems irrigation; mulching; soil | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

Full Text | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

Athmar Jameel Kareem Al-Lame
**It is noticed that superiority of the treatment of mulching with black nylon at the beginning and end of the season by obtaining the highest thermal conductivity of the soil, followed by the treatment of straw and fronds compared to the treatment without mulching, as it reached at the beginning of the season 0.830, 0.769, and 0.752 W∙m**^{−1}∙K respectively, and reached at the end of the season 0.772, 0.813, and 0.834 W∙m^{−1}∙K respectively, while the thermal conductivity of the control was 0.665, 0.746 W∙m^{−1}∙K at the beginning and end of the season respectively.**The basin irrigation method outperformed the furrow irrigation method in the thermal conductivity values at the beginning and the end of the season, reaching 0.733 and 0.775 W∙m**^{−1}∙K respectively at the beginning of the season and 0.785 and 0.797 W∙m^{−1}∙K respectively at the end of the season.**The black nylon mulch treatment outperformed the rest of the treatments at the beginning of the season, followed by the non-mulched treatment, then the frond mulching and straw mulching treatment by obtaining the highest heat flux rate of 2.96, 3.30, 4.47 and 6.80 W/m**^{2}, respectively.**The basin irrigation method outperformed the furrow irrigation method by obtaining the highest heat flux at the beginning of the season, reaching 5.99, and 2.77 W/m**^{2}, respectively, but the opposite happened at the end of the season where the furrow irrigation method outperformed the basin irrigation method, reaching 3.99, and 3.85 W/ m^{2}respectively.**The mulching treatment with black nylon exceeded by obtaining the highest values of volumetric heat capacity, then followed by the treatment of mulching with straw and fronds, and then treatment without mulching at the beginning and end of the growing season, reaching 1.61, 1.53, 1.49, and 1.39 MJ / m**^{3}respectively at the beginning of the season and 1.52, 1.54, 1.54 and 1.63 respectively at the end of the season.**The basin irrigation method outperformed the furrow irrigation method in that it obtained the highest values of volumetric heat capacity which were 1.48 and 1.53 MJ / m**^{3}.K respectively at the beginning of the season and 1.57 and 1.54 MJ / m^{3}.K respectively at the end of the season.**The treatment of mulching with black nylon outperformed by obtaining the highest value of thermal diffusivity, followed by the treatment of mulching with fronds and straw, compared to a treatment without mulching at the beginning of the season, which amounted to 5.18x10**^{-7}, 5.06x10^{-7}, 5.01x10^{-7}, and 4.79x10^{-7}m^{2}/ sec respectively.**The basin irrigation method achieved the highest rate of thermal diffusivity compared with the furrow irrigation method at the beginning of the growing season, reaching 5.09 x10**^{-7}, and 4.94x10^{-7}m^{2}/ sec respectively.
**I.****Introduction**
Soil temperature is one of the most important physical properties of soil, and researchers have been interested in studying its changes due to its effect on many of the chemical, physical and biological processes that occur near the root zone of the plant and the layer of air surrounding the soil surface [1]. The thermal properties of the soil are dynamic, because they depend on external factors such as weather conditions, tillage, and physical properties of the soil such as moisture content, temperature, bulk density, etc. [2], In view of the climatic conditions that our country and the countries of the Middle East region are exposed to due to global warming and the unprecedented rise in temperatures and their rates exceeding more than 50 Maize ( From this standpoint, this study came for the purpose of achieving the following goals: Study the effect of different types of soil mulching on the thermal properties of the soil.
The experiment was conducted in sandy loam soil. A factorial experiment was implemented according to the RCBD with three replications. The experiment land was plowed, smoothed, amended, and divided into 24 experimental units with dimensions 4 x 3.75 m, leaving a distance of 1 m between blocks and 1 m between the experimental units. Some physical and chemical properties of the field soil were measured before planting (Table 1 and 2), as well as the chemical properties of irrigation water (Table 3). The experiment consists of the following factors: **Soil Mulching: Three types of mulching have been used, namely:**- Black mulching, the plots were completely covered with black nylon, and as for the furrows, it was completely covered with black nylon, leaving the bottom of the furrow uncovered.
- Mulching Fronds, the plots were covered with fronds, and as for the furrow, the side facing the sun was covered with palm fronds where the crop was grown.
- Straw mulching, the plots were covered with straw and, for furrow, the side facing the sun on which the crop was grown.
- Without Mulching (Control).
**Irrigation method: It includes two types of irrigation methods, namely:**- Basins Irrigation (B)
- Furrow Irrigation (F)
The eight treatments were allocated randomly to the experimental units of each block. The planting was carried out on July 20, 2019 in lines in basins (plots) and in the upper third in furrow, the distance between furrow was 75 cm, and in the hole, the distance between one hole and another 25 cm
d = depth of irrigation water to be added (cm) Ө Өw = volumetric moisture before subsequent irrigation cm D = soil depth (cm), where a depth of 10 cm was used for the stage of germination and vegetative growth, then it was increased to 20 cm for the stage of flowering, then it was increased to 30 cm in the stage of maturity and harvesting, depending on the field follow-up to deepen the root system of the crop. The volume of added water (V) was calculated for each experimental unit and the irrigation time (T) according to the equations in [6] and [7] as follows:
d = depth of irrigation water (m) A = The area of the experimental unit (plots or furrows) m Q = discharge (liters / s) Soil bulk density was measured for all experiment treatments before planting and at the beginning, mid and end of the season and at five depths (0-10) (10-20) (20-30) (30-40) (40-50) cm from the soil surface using the method of Cylinder Core Sample. The soil water conductivity was measured for all the experiment treatments at the end of the season and at five depths (0-10) (10-20) (20-30) (30-40) (40-50) cm from the soil surface using a constant water column on non-disturbed soil according to the method [8] and according to the following equation:
As: _ K: V: The volume of leachate (cm³). L: Length of the column of soil (cm). A: The area of the running section (cm²). t: water collection time (hour). Δh : The change in the water voltage between its entry and exit point (cm).
Soil temperature was measured for all experiment treatments throughout the growing season and at depths of 0-30-20-20-10 cm from the soil surface by electronic thermometers every 6 hours on a daily basis throughout the experiment period. Thermal characteristics were calculated for all experiment treatments, including: - Calculating the thermal conductivity of the soil according to [9], using the following equation:
Where W = gravimetric moisture content% Yd = soil bulk density Mg / m - Soil heat flux is calculated from (Fourier) equation in [10] and as follows:
qh = heat flux (w / m k = thermal conductivity (w / m.k) T = temperature (K) X = vertical distance (m) - Estimation of the volumetric heat capacity (Cv) is calculated from the equation given in [10] following:
Cv = volumetric heat capacity (J / m Pb = bulk density (Mg / m Ɵ = volumetric soil moisture content (m - Estimation of thermal diffusivity (D) according to the following equation in [11]:
DH = thermal diffusivity m K = thermal conductivity w / m.k CV = volumetric heat capacity J / m
**III.****Results and Discussions****Thermal conductivity**
There are significant differences in the mulching treatments on the values of the thermal conductivity of the soil during the growing season of the crop (Figure 1), where it is noticed that the treatment black nylon mulching at the beginning and end of the season has the highest thermal conductivity of the soil, and then comes the treatment of straw and fronds compared to the control treatment, as it reached at the beginning of the season 830, 0.769, and 0.752 W∙m
Figure 2 shows a significant effect of the irrigation method factor on the values of the thermal conductivity of the soil during the growing season of the crop, as the basin irrigation method significantly outperformed the furrow irrigation by means of increasing the thermal conductivity at the beginning and end of the season, reaching 0.733 and 0.775 W∙m
Figure 3 shows a significant effect of the covering factor on the heat flux values of the soil during the growing season of the crop, where the treatment of mulching with black nylon surpassed the rest of the treatments at the beginning of the season, followed by the treatment without coverage, then the treatment of mulching with fronds and straw mulching, reaching 6.8, 4.47, 3.30, and 2.96 W∙m
There is a significant effect of the irrigation method factor on the heat flow values of the soil during the growing season of the crop (Figure 4), as it is noticed that the basin irrigation method is superior to the furrow irrigation method by obtaining the highest heat flux at the beginning of the season as it reached 5.99 and 2.77 W. m
It is noticed from Figure 5 that there is a significant effect of the mulching on the values of the volumetric heat capacity of the soil during the growing season of the crop. The treatment of mulching with black nylon outperformed by obtaining the highest values of the volumetric heat capacity, then comes the two treatments of mulching with straw and fronds, and then the control treatment at the beginning and end of the growing season It was 1.61, 1.39, 1.49, 1.53 MJ. m
It is noticed from Figure 6 the effect of the factor of the irrigation method on the values of the volumetric heat capacity of the soil during the growing season of the crop, where it is noticed the superiority of the basin irrigation method over the furrow irrigation method in that it obtained the highest values of the volumetric heat capacity, reaching 1.53, 1.48 MJ.m
It is noticed from Figure 7 the effect of the mulching factor on the thermal diffusivity values of the soil during the growing season of the crop. The black nylon mulching treatment outperformed by obtaining the highest thermal diffusivity value, followed by the frond mulching and straw mulching treatment compared to control treatment at the beginning of the season, reaching 5.18x10-7, 5.06. 10-7, 5.01x10-7, x10-7 4.79 m
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