loam

Currently, lack of water is one of the important problems in the agricultural sector, which affects the growth and development of plants. To deal with this problem, there are various management strategies that require checking the condition of the plant under deficit irrigation stress. deficit irrigation is one of the management strategies under water stress. In this way, although yield may decrease, this decrease is not significant compared to the profit caused by saving irrigation water consumption, reducing the costs of its extraction, transmission, distribution and storage for other products. Soil physical properties are important because of their important role in supporting plant growth. These characteristics determine interaction effects of the plant with soil, absorption of water and nutrients, penetration of the roots, soil temperature and the activity of microorganisms. Among the physical properties of soil, soil texture has a great influence. Satureja hortensis L is a one-year plant, it is suitable for cultivation in hot and dry areas with a lot of light. Considering the importance of medicinal plants and the few researches have been conducted on the effect of deficit irrigation stress and different soil textures on Satureja hortensis L, the purpose of this research was to investigate the effect of irrigation levels and soil texture on some characteristics and water productivity of Satureja hortensis L.

In order to Investigating the effect irrigation levels and soil texture on some characteristics and water productivity of Satureja hortensis L , a factorial experiment was conducted based on a completely randomized design with 3 replications and based on pot culture in 2023 in the experimental research greenhouse at university of Torbat-e Jam, In this experiment, the treatments consisted of 3 levels of irrigation (100, 75 and 50% of water requirement) and three soil textures (loam, clay loam and sandy loam). Class A evaporation pan was used to determine water requirement and water treatments were applied based on it. In this research, the number of nutritional needs of plants at the beginning of the experiment was estimated based on reliable scientific sources and the same amount was provided to the plants so that each plant received its required nutrients at the end of the growth period. Satureja hortensis L plant coefficients for initial, development, and middle growth stages were considered 0/45, 0/78, and 1/3, respectively. irrigation cycle was considered every other day. In this study, plant height, shoot and root dry weight, crown area, chlorophyll a, chlorophyll b, total chlorophyll, percentage of essential oil, proline and water productivity were measured.

The results showed that the application of deficit irrigation at the rate of 75 and 50% of the water requirement resulted in reduction of 11.62 and 23.37% of plant height, 23.71 and 50.55% of shoot dry weight and 23.96 and 52.73% root dry weight respectively compared to the control treatment (100 percent water requirement). Also, the total amount of water consumed by each pot in the treatment of 100, 75 and 50% of water requirement was 12.505, 9.378 and 6.252 liters, respectively, and the results showed that with the application of deficit irrigation, the water requirement from 100% to 75 and 50 The percentage of water requirement, the highest level of water productivity was obtained in loam and sandy loam soil in the 75% water requirement treatment and in clay loam soil in the control treatment (100% water requirement). based on the results of this research, it can be said that Satureja hortensis L was sensitive to the stress of deficit irrigation and the application of stress will lead to a decrease in the yield and yield components of this plant. Also, based on the results of this research, the most suitable soil texture for the better growth of the aerial parts of the Satureja hortensis L is loamy texture, so that the highest amount of plant height, dry weight of aerial parts, dry weight of roots, crown surface, chlorophyll a, chlorophyll b and total chlorophyll assigned to himself. Also, the best soil texture in terms of essential oil percentage and proline content was clay loam soil. Considering that the yield of the Satureja hortensis L in the condition of 75% deficit irrigation stress did not decrease much and also due to the lack of water in some areas, it is recommended to use 75% deficit irrigation treatment in the conditions of using loamy soil, in greenhouse conditions.

Sustainable agriculture at arid and semi-arid areas depends on optimized usage of fresh water resources. Evaporation from soil surface and deep percolation categorized as unuseful losses at irrigation, so their reduction could increase the root water uptake efficiency and yield production. Subsurface drip irrigation could provide this situation. Proper depth for installing dripper is the place that reduces soil surface evaporation and deep percolation. The objective of this study was to investigate the effects of various dripper installation depth on soil water content distribution and root water uptake and to choose the proper depth. For this purpose, HYDRUS-2D software was used to investigate the effect of three factors on non-beneficial losses and consumed water in drip irrigation, numerically. These factors were soil texture (loam, clay loam and sandy loam), installation depth (0, 10, 15 and 20 Cm) and dripper discharge (1, 2, 4 and 8 l.h-1). The results showed, although increasing the installation depth could reduce cumulative evaporation up to 40%, but the best installation depth was 15 Cm with discharge rate of 1 l.h-1, according to the amount of deep percolation and consumed water. The effect of soil texture was more than the effect of installation depth on the amount of irrigation water, so that the amount of irrigation water in 2 l.h-1 discharge rate was 2.9, 3.1 and 4.6 m3.m-1 for loam, clay loam and sandy loam soil texture, respectively. Also, for clay loam texture, dripper discharge had the highest effect on root water uptake and the installation depth had the lowest effect on soil surface evaporation.

The relation between water table depth and evaporation rate from bare soil is of great importance in arid and semi-arid areas. In this region, due to over irrigation, the water table is very close to the ground surface which leads to salinization of the soil. Evaporation from soil columns in the presence of a water table is a important that has received great attention for many decades. The soil-drying process has been observed to occur in three recognizable stages. The first stage is evaporation with constant intensity. Secondly, evaporation is in descending order. The third stage is the residual evaporation of low intensity, which begins after excessive drying of the surface layer of the soil and its effect on reducing the hydraulic conductivity of the soil. Precise determination of evaporation from bare ground surface in semi-arid or arid regions then becomes critically important. The purpose of this study was to determine the effect of water table depth on the evaporation from soil surface, as well as the determination of different evaporation stages.

The soil used in this experiment was loam with a bulk density of 1.32 gr/cm3. The experiment was conducted in a greenhouse and the duration was 74 days. Soils Were sived through a 2-mm mesh and then packed into the soil columns using soil funnel. The soil columns were cylindrical PVC tubes of 200 mm inside diameter. Water table was stabilized at depths of 400, 600 and 800 mm from the soil surface, and the experiment was repeated twice. For stabilizing the water table in different depths, Each soil columns contained a pipe from the botton, to supply water from bottles that maintained the water table constant. The water losses from the soil profile was measured at different depths and times using Delta-T Device Moisture Meter.

The results showed that water content between 0 and 160 mm in the soil column were decrease during the experiment and close the water table depth remained saturated. In the steady-state, the rate of water loss from bottle next to the soil column is equal to the rate of evaporation from the soil surface. In a non steady-state, the rate of evaporation equals the sum of the rate of water loss from bottle and the water depleted from the soil profile. The maximum evaporation from the the water table was related to a depth of 400 mm and equal 384.6 mm and the highest water loss from the soil profile was related to a depth of 800 mm and equal 51.3 mm. By increasing the water table depth from 400 to 800 mm (increased 100%), the evaporation rate from the water table 24 percent and the total evaporation from the soil surface decreased by 16.5 percent. The length of the first stage of the evaporation for the water table depth 400 mm was 2 days and for 800 mm less than 1 day.

The results of this study gave us information on the flow of water above the shallow water table. Water content changes in the soil surface soil are higher than close watertable. Movement of water close water table is liquid and close the soil surface is vapor. The duration of the first stage of evaporation has decreased with increase water table depth. In general, it can be concluded that evaporation from the water table can provide a large portion of the water requirement by the plants.

Salinity and organic matter deficiency are the main problems of soils in arid and semi-arid regions. The use of residues in presence of salinity may affect soil properties differently. In this research, the effect of zero, 1. 5%, 3%, and 4. 5% application of pistachio residues and electrical conductivity (salinity) of water including three levels of 4, 8, and 12 dS m-1 were investigated on water repellency of soils with three different textures, namely, silty clay, loamy, and loamy sand. The static and dynamic water repellencies were determined by measuring soil-water contact angle and water penetration time. The mean values of soil-water contact angle for clay, loam, and sandy loam soils were 70±2. 5º, 65±2. 6º, and 62 ±3. 4º, and water droplet times (WDPT) were about 35±2. 6, 26±1. 6, and 18±0. 6 s, respectively. Accordingly, static water repellency of the fine textured soil was more than that of the medium and coarse textured soils by 3% and 7%, respectively, while the dynamic water repellency was 24% and 95% more, respectively. Salinity had no significant effect on static or dynamic water repellency. However, the salinity of 12 dS. m-1 increased the static water repellency of clay soil by 7%. The residues increased the static and dynamic water repellency of soils, except in silty clay soil where the effect of residues on static water repellency was not significant. In general, salinity levels had no significant effect on the mean values of the static and dynamic water repellency of soils; whereas application of residues (except for 4. 5% residues) increased both static and dynamic water repellency. Furthermore, since the applied residues were probably not fully decomposed in the time period used in this study, it is recommended that longer or different time periods be used in the future studies.