Mediterranean Agriculture

Mediterranean agriculture is found in the areas surrounding the Mediterranean Sea and in areas with a similar climate, characterized by mild, wet winters and hot, dry summers 5 . There are four land-use patterns that characterize the traditional Mediterranean farming system 5 extensive wheat cultivation extensive grazing by sheep and goats cultivation of tree crops such as olives and figs, grapes, and date palms cultivation of fruits and vegetables, with apples, peaches, and pears as most...

Soil Heat Flux Density G

For daily calculations, G (MJ m-2 day-1) can be estimated using a simplified approach to the heat balance of the soil profile where T is the mean daily air temperature ( C), T-1 is the mean air temperature ( C) of the preceding three-day period, and 0.1 is an empirical conversion factor (MJ m-2 day-1 C-1). Because the magnitude of daily soil heat flux beneath densely planted grass is relatively small, it can be neglected (i.e., G 0). For monthly time-step calculations, G can be computed from...

Description ofSystems

The practice of surface irrigation is ancient and is used on more than 90 of the world's irrigated area. The sustainability of irrigated agriculture depends on improvements and innovations in surface irrigation methods, their appropriateness for the different systems, and their adoption in field practice. Surface irrigation methods include several processes of water application to irrigated fields 16 furrow, basin, border, contour ditches (wild flooding), and water spreading. The two last...

Average Crop Coefficients

A simple procedure is used to construct the Kc curve for the complete growing period. This procedure was first presented by Doorenbos and Pruitt 55 . The Kc curve, such as that shown in Fig. 5.5, is constructed using the following three steps 1. Divide the growing period into four general growth stages that describe crop phenology or development, and determine the lengths of these stages, in days. The four stages are initial period, crop development period, midseason period, late-season period....

Other Types of Road Construction

Roads with continuous pavement are much appreciated for such leisure activities as bicycling, jogging, or rollerskating, although avoided by other users such as ramblers. In vulnerable areas, objections often are raised to pavement for reasons that have to do with the landscape. Many spur roads are built in such areas, a variation that has proven its worth. The tracks for vehicles usually are made of concrete, with grass in between Figure 3.15. Nomogram for the construction of roads with low...

Moving Lateral Systems

These systems have laterals that move continuously while applying water. There are three main types of systems center pivot, lateral move, and side move (for complementary information see 11, 94-96, 99 ). These systems consist of a single galvanized steel lateral that rotates in a circle about a fixed pivot point in the center of the field (Fig. 5.27). Lateral pipe diameters range from 100 to 250 mm. The lateral is supported using cables or trusses as much as 3 m above the ground on A-shaped...

Substratum and Foundation

The optimum requirements will have been met if the subsoil has excellent bearing capacity and also can be used as building material, which can reduce the construction costs drastically. Unfortunately, such conditions are rare. Most sites either have been developed already or lack the appropriate dimensions. Geology is differentiated only Figure 3.12. Standard cross section of a minor rural road. Source Adapted from 23 . Figure 3.12. Standard cross section of a minor rural road. Source Adapted...

Planning for the Opening Up of Developing Rural Areas

Today, planning issues regarding the opening up of areas that are solely agricultural are confined mainly to developing countries. Especially in these countries remoteness, isolation, and inaccessibility are key characteristics. Moreover, the economic and social deprivation that these areas suffer is often largely due to inadequate transportation services. Investment in transport facilities is usually just one element of an integrated development program. This is designed to improve standards...

Sprinklers

Sprinkler heads are the most important component in the system because their performance determines the effectiveness and efficiency of the whole system. A sprinkler operates by forcing water under pressure through a small hole or nozzle and into the air. Nozzle size and water pressure determine the flow rate. Most sprinklers are designed to give a circular wetting pattern. The distance from the sprinkler to the outer edge of that circle is called the throw or wetted radius. Nozzle design,...

Field Evaluation

Field evaluation of sprinkler systems in operation can play a major role in improving irrigation performance. Field evaluations of set systems include the following observations 10, 11, 19, 110 pressure at the sprinkler nozzles at different locations pressure variation A P along a lateral and within the operating set sprinkler discharges and respective variations along a lateral and within the operating set applied depths in a sample area on both sides of a lateral or between two laterals...

Planning for the Opening Up of Agricultural Areas

Several studies are available on so-called optimal agricultural field length. Boss and Flury 4 cite a Swiss study from the early 1980s. This study shows that fields suitable for arable farming require a road on both sides, whereas one road is sufficient for grassland. Figure 3.7. Optimum field lengths for a 16-ha farm with several crop cultivations. Source 4 , reprinted by permission of PUDOC-DLO, Wageningen. Figure 3.7. Optimum field lengths for a 16-ha farm with several crop cultivations....

Preface and Acknowledgments

Land and Water Engineering are becoming increasingly important globally for the future of humankind. There are at least two main reasons for this growing significance First, it is well understood that, aside from several other means, the wise use of land and water will play a key role in the provision of enough good food for future generations. Despite all types ofprograms and policies, the global population still increases and most probably will continue to do so for the next half century or...

Definition of Reference Evapotranspiration

The primary purpose for developing ET0 equations is to estimate a reference ET by which a crop coefficient is multiplied to obtain an estimate of crop ET. In many instances, the ET0 equation has represented a hypothetical living crop reference in order to provide for a complete record of ET0 during the development of crop coefficients and during calibration or analysis of other ET equations. Wright and Jensen 53 and Wright 71 utilized a hypothetical alfalfa ET0 Jensen 54 and Jensen et al. 2...

Yield Irrigation Depth Relationships

Irrigation is the primary management practice that is utilized to increase crop yields (or to permit crop production) in semiarid and arid climates. In addition, irrigation is used to stabilize crop yields when rainfall is unreliable in subhumid and humid climates. Including irrigation depths (IR) in the ratios of DM production or marketable yield (Y) to transpiration (T) or evapotranspiration (ET) is necessary when making both engineering and economic decisions, to determine the optimal...

General Aspects

Microirrigation, also called trickle or drip irrigation, applies water to individual plants or small groups of plants. Application rates are usually low to avoid water ponding and minimize the size of distribution tubing. The microirrigation systems in common use today can be classified in two general categories Drip irrigation, by which water is applied slowly through small emitter openings from plastic tubing. Drip tubing and emitters may be laid on the soil surface, buried, or suspended from...

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Cablegation Method

Appropriate control of inflow rates and duration of irrigation is particularly relevant where overirrigation has to be avoided. This is the case when deep percolation of excess water contributes to water table rise, salinization, leaching of fertilizers and other agrochemicals, and excessive drainage volumes. Such control is also essential when irrigating saline soils or using saline water. Therefore, the improved control of qin and co becomes not only a matter of irrigation performance but...

Irrigation Management Under Water Shortage Conditions

The lack of water has a negative effect on the whole set of vital plant processes such as photosynthesis, respiration, absorption of nutrients, and assimilate translocation. It also affects growth, reproduction, and the development of the seed. From the agronomical point of view, the main interest is focused on the effect of water deficit on yield. The effect of water stress on plant development and productivity has been the object of several studies 32-35 and is dealt with in Section 5.5. The...

References

Updated evapotranspiration and crop water requirement definitions. Crop Water Requirements, eds. Perrier, A., and C. Riou, pp. 885-887. Paris INRA. 2. Jensen, M. E., R. D. Burman, and R. G. Allen (eds.). 1990. Evapotranspiration and Irrigation Water Requirements. ASCE Manuals and Reports on Engineering Practices No. 70, New York. 3. Doorenbos, J., and W. O. Pruitt. 1975. Guidelines for Predicting Crop Water Requirements, FAO Irrigation and Drainage Paper 24, Rome FAO. 4....

Mobile Raingun Systems

Mobile raingun systems (also called traveling sprinklers or travelers) use a large rotary sprinkler operating at high pressure. The term raingun is used because of the large size of sprinkler used and its ability to throw large quantities of water over wide areas. They have become popular because of their relatively low capital cost and low labor requirements. They are well adapted to supplemental irrigation. Because of the high pressure requirements, they have high energy costs. Rainguns...

Soil Water Potential

Water present in an unsaturated porous medium such as soil is subject to a variety of forces acting in different directions. The terrestrial gravitational field and the overburden loads due to the weight of soil layers overlying a nonrigid porous system tend to move the soil water in the vertical direction. The attractive forces occurring between the polar water molecules and the surface of the solid matrix and those coming into play at the separation interface between the liquid and gaseous...

Reclamation Procedures

Methods of reclamation have to be tailored to the specific problems at hand. However, there are some principles that are common to all reclamation procedures. Figure 4.7 shows the steps and the considerations that are necessary in the design of a suitable reclamation scheme. We have to bring back to full life an ecosystem in which normal biological processes are at a standstill. The natural development of such an ecosystem normally takes a long time, and so, the key to improvement is upgrading...

Balancing Agriculture Between Development and Conservation

Increasing agricultural production has always been the main goal of agricultural research. Because of the continuing growth of the world's population and the important share of agricultural products in the world economy, this increase of agricultural production will continue to be important, but under different conditions. The more or less uncontrolled growth in agricultural production during the past few decades, in industrial as well as developing countries, has pushed agricultural production...

Measurement of Soil Losses from Erosion

Soil Erosion Stages

The characteristics of the experimental site are determined by the experimental objectives and the type of data to be obtained. Generally, plots are used to study physical phenomena affecting soil detachment and transport whereas complex hill slopes or small watersheds are gauged for examining deposition processes and therefore sediment yield. In an experimental station for soil erosion studies, bounded runoff plots of known width, slope length, slope steepness, and soil type are monitored....

Case When Wind Speed Data Are Missing

Two approaches can be utilized to overcome the problem of missing windspeed data. Use of Wind-Speed Data from a Nearby Weather Station. Importing wind-speed data from a nearby station, as for Rs discussed earlier, relies on the fact that airflow above a homogeneous region may have relatively large space variations during the course of a day but small variation over longer periods or even over the day itself. This occurs when air masses are of the same origin or when the same fronts govern...

The Penman Monteith ET0 Equation

The grass reference crop in the above definition can be fully described using the PM approach. The grass reference crop is probably, together with alfalfa, the best-studied crop regarding its aerodynamic and bulk stomatal characteristics 2, 21, 59, 60 . The aerodynamic resistance ra (Eq. 5.4) can be calculated easily because the zero plane displacement height can be estimated from the crop height h, d 0.67h the roughness height for momentum transfer can be given by zom 0.123h and the roughness...

Crop Water Models

Agricultural planning is a wide management field 88 . Irrigation management consists of determining when to irrigate, the amount to apply at each irrigation and during each stage of plant growth, and the operation and maintenance of the irrigation system. The primary objective is to manage the production system for profit without compromising the environment. The major management activity involves irrigation scheduling. Most irrigation water management concepts include salinity control and the...

Stabilizing Structures for Gullies and Embankments

The mechanics of gully erosion can be reduced to two main processes 24 down-cutting and headcutting. Downcutting of the gully bottom leads to gully deepening and widening. Headcutting extends the channel into ungullied headwater areas and increases the stream net and its density by developing tributaries. Thus, effective gully control must stabilize both the channel gradient and the channel headcuts. Where an effective vegetation cover will grow, gradients can be controlled by the establishment...

Measurement of Water Content of Soil

The measurement of water content in the soil is of great importance in many investigations and applications pertaining to agriculture, hydrology, meteorology, hydraulic engineering, and soil mechanics. In the fields of agronomy and forestry, the amount of water contained in the soil affects plant growth and diffusion of nutrients toward the plant roots, as well as acting on soil aeration and gaseous exchanges, with direct consequences for root respiration. Also, continuous monitoring of soil...

Types of Erosion and Its Assessment

Soil is a vital resource for the production of renewable resources for the necessities of human life, such as food and fiber. Soils, however, essentially are nonrenewable resources 1 . According to Golubev 2 , the area of cultivated land in the world is 14.3 million km2. In cultivated areas, drastic changes in vegetation have occurred and instead of dense natural vegetation cover, bare soil often is exposed for most of the year with sparse crop vegetation existing for a few months. These...