Irrigation Scheduling

Native tree plots have been established in river irrigation districts in the western U.S. to provide habitat for threatened and endangered birds. Information is needed on the effective irrigation requirements of the target species. Cottonwood (Populus spp.) and willow (Salix gooddingii) trees were grown for seven years in an outdoor plot in a desert environment in Tucson, Arizona. Plants were allowed to achieve a nearly complete canopy cover over the first four years, then were subjected to three daily summer irrigation schedules of 6.20 mm d−1; 8.26 mm d−1 and 15.7 mm d−1. The lowest irrigation rate was sufficient to maintain growth and high leaf area index for cottonwoods over three years, while willows suffered considerable die-back on this rate in years six and seven. These irrigation rates were applied April 15–September 15, but only 0.88 mm d−1 was applied during the dormant period of the year. Expressed as a fraction of reference crop evapotranspiration (ETo), recommended annual water applications plus precipitation (and including some deep drainage) were 0.83 ETo for cottonwood and 1.01 ETo for willow. Current practices tend to over-irrigate restoration plots, and this study can provide guidelines for more efficient water use.

Irrigation frequency is one of the most important factors in irrigation scheduling, and a proper irrigation frequency can establish moderate moist and oxygen conditions in the root zone throughout the crop growth period. This study was conducted to study the effect of scheduling irrigation on the water use efficiency and yield of cabbage. It was conducted on a cabbage farm within the Ho Municipality. The weights of harvested cabbage heads were recorded. Four raised beds were prepared with two replication labelled into various treatment (T1, T2, T3, and T4). Treatment 1 was irrigated every day, Treatment 2 irrigated three times in a week, Treatment 3 irrigated only once in a week and Treatment 4 was under control (No irrigation). Treatment 1 (T1) yielded the highest weight(kg) of cabbage head after harvesting and the lowest water use efficiency as compared to yields of treatment 2 and 3 with treatment 4 yielding the least in weight of cabbage heads. The relationship between yield and...

А complex biophysical model for prognosis and for operative rnanagement of the irrigation regime on maize fields was tested. The basic eIements of the model were the combinational equation of Penman, the equaton оf water deficit in the water supplying soil laуеr, the average climatic correlation оf potential evapotranspiration and some physical  and biological regularities in the system soil-plant massif-atmosphere.

A field experiment was conducted for three consecutive years from 2011 to 2013 to study the effect of different irrigation scheduling through drip irrigation on papaya (Carica papaya Linn.) production in sandy loam soil. The experiment comprised of nine treatments under drip method of irrigation with combination of three irrigation regimes viz. 60%, 80% and 100% of cumulative pan evaporation (CPE), three different levels of fertilizer, and conventional irrigation at 50 mm CPE as a control treatment. The results showed that drip irrigation resulted in 45 to 66 % water saving with 21 to 36 % increase in papaya yield as compared to conventional method of irrigation. The water use efficiency was found maximum (3.39 t/ha/cm) in drip irrigation with 60 per cent cumulative pan evaporation (CPE) on daily basis. The drip irrigation at 100% CPE with 100% recommended dose of fertilizer (RDF) was found to be optimum for growth (139.17 cm), and papaya production (112.55 kg/plant)..

Bandaragoda, DJ; Rehman. 1995. Warabandi in Pakistan's canal irrigation systems: Widening gap between theory and practice. Colombo, Lanka: International Management Institute. pp. xx, 89. Country Paper, Pakistan No. 7) /irrigation scheduling/irrigation systems irrigation ...

Irrigation scheduling based on the daily historical crop evapotranspiration (ETh) data was theoretically and experimentally assessed for the major soil-grown greenhouse horticultural crops on the Almería coast in order to improve irrigation efficiency. Overall, the simulated seasonal ETh values for different crop cycles from 41 greenhouses were not significantly different from the corresponding values of real-time crop evapotranspiration (ETc). Additionally, for the main greenhouse crops on the Almería coast, the simulated values of the maximum cumulative soil water deficit in each of the 15 consecutive growth cycles (1988–2002) were determined using simple soil-water balances comparing daily ETh and ETc values to schedule irrigation. In most cases, no soil-water deficits affecting greenhouse crop productivity were detected, but the few cases found led us to also assess experimentally the use of ETh for irrigation scheduling of greenhouse horticultural crops. The response of five greenhouse crops to water applications scheduled with daily estimates of ETh and ETc was evaluated in a typical enarenado soil. In tomato, fruit yield did not differ statistically between irrigation treatments, but the spring green bean irrigated using the ETh data presented lower yield than that irrigated using the ETc data. In the remaining experiments, the irrigation-management method based on ETh data was modified to consider the standard deviation of the inter-annual greenhouse reference ET. No differences between irrigation treatments were found for productivity of pepper, zucchini and melon crops.

Since HEISs are relatively a new intervention in South Asia, there exists a dearth of relevant printed material regarding various operational aspects of the systems especially in relation to preparation of fertigation, irrigation and chemigation schedules. Perhaps, the most critical and the most wanted facet of these newly introduced systems is the preparation of proper irrigation schedules for various crops being grown in their command. In addition, the training of project staff and the users of the systems regarding these schedules covering their understanding and implementation in the field appears to be a missing link. A fair analysis of the factors leading to such gaps reflects that lack of technical material on the subject is the primary reason.
The effort made by PSC in the form of this manual is expected to serve the purpose in question. Solved examples of preparation of schedules for a number of crops have been added to give an in depth orientation to the reader. Through requisite review of this manual, it will not only be possible to check and monitor the irrigation schedules supplied on some of the sites by the SSCs for their authenticity and accuracy but it will also enable the project staff especial ly the HEIS teams to prepare and provide the same at the farms/sites without these schedules on instant basis.