Effects of Drip Irrigation with Plastic on Photosynthetic Characteristics and Biomass Distribution of Muskmelon

An experiment was conducted in China to develop guidelines for the mulching drip irrigation of commercial muskmelon crops. Three sets of factors were laid out in rows to give a three × three factorial design. First, plastic covers were placed over the entire growing area (rows and inter-rows, or full), over the rows (half), or no plastic applied (none). Second, there was one irrigation pipe per row (T1), three pipes for four rows (T3/4), or one pipe for two rows (T1/2). Finally, the plants were irrigated when the soil water content fell to 60%, 70%, or 80% of field water capacity (FC). Information was collected on net CO2 assimilation (Pn), plant growth, and yield. Overall, maximum Pn occurred with half plastic covering, one irrigation pipe for two rows, and irrigation at 80% FC. Plant fresh weight was higher with half plastic covering, one irrigation pipe per row, and irrigation at 70% or 80% FC. Yield was higher with half plastic covering, and irrigation at 70% or 80% FC. There were only small differences in the yield across numbers of irrigation pipes. These results suggest that overall productivity was better with plastic covers over the rows and irrigation at 70% or 80% FC. Differences in productivity with different numbers of irrigation lines per row were small.

The assessment of erosion in Aoulai watershed (central Rif mountains, Morocco) based on the PAP-RAC guidelines application

The land in the Aoulai watershed in the Rif mountain area of northern Morocco has been deteriorating continually due to several different forms of erosion. The Aoulai watershed is essentially characterized by the domination of weak resistance of the rocky formations and its sensitiveness to other major internal factors that result in a conspicuous impetus for both mass movements and water erosion.Water erosion is seen as the most damaging phenomenon for nature in northern Morocco because it acts as an obstacle to the natural balances and seems to have greater effect on the slopes, through the influence of both human and natural factors. To assess and examine the erosion phenomenon, we have chosen to conduct a qualitative assessment of water erosion in the Aoulai watershed using the PAP-RAC (Priority Actions Programme/Regional Activity Centre) Guidelines. This is the methodology that is most widely applied and implemented both for determining and identifying the areas at risk of erosion and for supporting projects to reduce the degradation that has become a major threat to hydraulic structures including dams, irrigation pipes and other infrastructure elements, which are damaged by the erosion phenomenon in the Central Rif mountains of northern Morocco.

Design and Testing of a Punching-on-Film Precision Hole Seeder for Peanuts

HighlightsThe designed precision seeder meets the agronomic requirements for on-film hole seeding.Influencing factors were found by studying the operating principle and key parameters.A response model was successfully built and verified by experiments.This study provides technical support for punching-on-film hole seeding technology.Abstract. To satisfy the agronomic requirements for punching-on-film precision seeding of peanuts, a precision hole seeder was designed in this study. The seeder can perform simultaneous functions of film mulching, film punching, pipe laying, precision hole seeding, and seed covering. The overall structure and operating principle of the device were analyzed, and its major components, including a seed-metering device, soil-covering roller, and drip irrigation pipes, were theoretically studied. To optimize the operating parameters and achieve favorable performance, a three-factor quadratic orthogonal test was performed to test the effects of the vacuum chamber pressure, advancing speed of the seeder, and height of the type hole boss on the seeding performance; the variance and range of the test results were analyzed accordingly. Through the field experiments, when the vacuum chamber pressure, advancing speed of the seeder, and height of the type hole boss were optimized to 7.5 kPa, 4.2 km h-1, 5.3 mm, respectively, the qualification index, re-seeding index, and miss-seeding index of the seeder were 92.7%, 3.8%, and 3.5%, respectively. Thus, the developed seeder satisfies the agronomic requirements, and the study results provide a technical reference for the punching-on-film precision seeding of peanuts. Keywords: Model, Peanut, Precision seeding of peanut, Punching-on-film hole, Seeder.

Photo-Oxidative and Soil Burial Degradation of Irrigation Tubes Based on Biodegradable Polymer Blends

: Irrigation tubes based on biodegradable polymers were prepared via an extrusion-drawing process by Irritec and compared to conventional pipes made of high-density polyethylene (HDPE). A commercial polylactide/poly (butyleneadipate-co-butyleneterephthalate) (PLA/PBAT) blend (Bio-Flex®) and Mater-Bi® were used. The polymers were characterized from rheological and mechanical points of view. Irrigation pipes were subjected to photoaging with continued exposure to UV radiation up to 22 days. The degradability in the soil of irrigation tube samples was studied. The influence of temperature and UV irradiation on soil burial degradation was investigated. A soil burial degradation test was carried out at 30 °C and 50 °C for up to 70 days. The degree of degradation was evaluated from the weight loss percentage. The degradation rate of irrigation tube samples based on Mater-Bi® was higher at 30 °C and was stimulated after 14 days of UV irradiation. Higher temperatures or UV aging encouraged the disintegration in soil of Bio-Flex®-based irrigation tubes. Furthermore, tube samples, before and after UV and soil burial degradation, were analyzed by Attenuated Total Reflection–Fourier Transform Infra-Red (ATR-FTIR) spectroscopy.

VERTICAL SUB IRRIGATION

Since millennia, in areas of low rainfall, surface irrigation has been utilized. In 1959 the Israelian inventor Simcha Blass developed a patented very efficient plastic nozzle for dripping the irrigation water from plastic pipes over the crops cultivated soils. In occasion of a FAO project in Libya, this system was utilized for establishing a table grape plantation. In order to support each grape plant, instead of wood poles, plastic pipes of 5 cm diameter, 2.5 mt high were used, dipped into the soil some 50-60 cm, close to each plant. Out of 15 rows, 150 mt long, provided with the normal drip irrigation pipes, in 2 rows a technical modification of “drip irrigation” was used, in which the horizontal water pipe posed on the soil, with holes for dripping the water, was substituted with a normal plastic pipe, without holes, hanged on the plastic vertical poles. In this pipe, close to each grape plant, was made a small hole, in which was inserted a small plastic pipe (like the ones used for blood transfusions). The other side of these mini pipes were inserted into the big vertical plastic pipes used as a support to each plant vegetation, in order to convey the irrigation water deep into the soil. This system has been called “Vertical Subirrigation Technology”. In the summer of the third year of grape cultivation, the electric pump failed and, after a month, only the 2 rows with the modified system did not show any damage. This system was adopted in other FAO projects in the Near East, also for fertile-irrigation.

The effect of calcium on biofilm formation in dairy wastewater

Biofilm formation in dairy wastewater system irrigation pipes can reduce treatment capacity, increasing maintenance and cleaning costs. Understanding the effect of different components in the wastewater on growth and yield of bacteria present could help prevent excessive build-up of biofilms. This study investigated, in aerobic and anaerobic conditions, the effect of calcium, sodium and magnesium concentrations on growth rates, yields and saturation constants of four known biofilm forming bacteria associated with the blockage of an irrigation system. The ions tested (Ca2+, Mg2+, Na+) varied growth rates with biofilm growth in the presence of calcium being significantly slower (P < 0.05) than planktonic growth in sodium. Along with the slower growth, the addition of Ca2+ (up to 0.1 M) increased biofilm formation while addition over 0.5 M prevented biofilm formation. Knowing the nutritional requirements of the bacteria and the effects of the ions will be useful in predicting the growth, development and strategies in controlling biofilm formation in dairy wastewater.

Seepage Rate from Ceramic Pitchers under Positive and Negative Hydraulic Head

Picher irrigation is a traditional technique used to supply water to plants under drought conditions in arid regions. Laboratory experiments were conducted to evaluate water seepage rates from ceramic pots/pitchers, made from baked clay-sand local materials, under various environmental and hydraulic conditions. Seven ceramic pots (simulating ceramic emitters) with various dimensions were used in the experiments. Handmade ceramic pots of about 1 L in volume and 26 cm tall were used in the experiment. The hydraulic conductivities of the pots were measured using falling head method and the values ranged from 0.275 to 0.704 mm/d. Seepage rate from ceramic pots were measured in the air and when buried in the soil under constant and falling head method inside a temperature and humidity-controlled chamber. Results indicated that seepage rate is affected by various conditions including potential evaporation, soil suction pressure and moisture condition, and hydraulic head. Seepage rate from ceramic pots were higher under constant head condition and when buried inside soil than that under falling head or in the air. Seepage rates were found to increase steadily with potential evaporation but decrease gradually with increased soil moisture around ceramic pots. The value of hydraulic head seemed to have the largest effect on pitchers’ seepage rate. The seepage rate under a constant head of 30 cm above the mouth of the ceramic pot tested in the experiment was 2500 mL/d but decreased to only 114 mL/d under a constant head of -25 cm below the mouth of the pot. The experiments revealed that ceramic pitchers can be used to supply water even under negative head thus eliminating the need for pressurized flow inside irrigation pipes. Keywords: Arid regions, Drylands, Evaporation, Hydraulic head, Pitcher irrigation, Subsurface irrigation.

Internal surface roughness of plastic pipes for irrigation

ABSTRACT Assuming that a roughness meter can be successfully employed to measure the roughness on the internal surface of irrigation pipes, this research had the purpose of defining parameters and procedures required to represent the internal surface roughness of plastic pipes used in irrigation. In 2013, the roughness parameter Ra, traditional for the representation of surface irregularities in most situations, and the parameters Rc, Rq, and Ry were estimated based on 350 samples of polyvinyl chloride (PVC) and low-density polyethylene (LDPE) pipes. Pressure losses were determined from experiments carried out in laboratory. Estimations of pressure loss varied significantly according to the roughness parameters (Ra, Rc, Rq, and Ry) and the corresponding pipe diameter. Therefore, specific values of roughness for each pipe diameter improves accuracy in pressure losses estimation. The average values of internal surface roughness were 3.334 and 8.116 μm for PVC and LDPE pipes, respectively.