Rainfed Research Articles

Effects of change of use of land on an aquifer in a tectonically active region

This paper shows the effects caused by the combination of two factors: an anthropic factor and one natural. The leading causes of imbalance in the subsoil due to drawdown of the aquifer is reflected on the surface with the appearance of cracks on ground, then came the lateral and vertical movements called faulting. This geological phenomenon is due to a pattern of orientation is associated with a regional fault system, lateral movement is almost imperceptible but the vertical displacement becomes important because it is the most conspicuous and be responsible for the damage caused to the urban infrastructure, vertical faulting is related to the drawdown generated by intense extraction of groundwater. The demand for groundwater, increasing year by year in the past four decades because of the change in land use, the most significant change was the shift from rain feed crop to irrigated crop agriculture, this change in land use occurred on Celaya’s Valley between year period 1976-2009 was quantified by use of remote sensing and geographic information systems (GIS).

Floret development and grain setting differences between modern durum wheats under contrasting nitrogen availability.

Wheat yield depends on the number of grains per square metre, which in turn is related to the number of fertile florets at anthesis. The dynamics of floret generation/degeneration were studied in contrasting conditions of nitrogen (N) and water availability of modern, well-adapted, durum wheats in order to understand further the bases for grain number determination. Experiments were carried out during the 2008–2009 and 2009–2010 growing seasons at Lleida (NE Spain). The first experiment involved four cultivars (Claudio, Donduro, Simeto, and Vitron) and two contrasting N availabilities (50 kgN ha–1 and 250 kgN ha–1; N50 and N250) while experiment 2 included the two cultivars most contrasting in grain setting responsiveness to N in experiment 1, and two levels of N (N50 and N250), under irrigated (IR) and rainfed (RF) conditions. In addition, a detillering treatment was imposed on both cultivars under the IR+N250 condition. The number of fertile florets at anthesis was increased by ~30% in response to N fertilization (averaging across treatments and spikelet positions). The effect of N and water availability was evident on floret developmental rates from the third floret primordium onwards, as these florets in the central spikelets of all genotypes reached the stage of a fertile floret in N250 while in N50 they did not. In this study, clear differences were found between the cultivars in their responsiveness to N by producing more fertile florets at anthesis (through accelerating developmental rates of floret primordia), by increasing the likelihood of particular grains to be set, or by both traits.

Marginal analysis of water productivity function of tomato crop grown under different irrigation regimes and mulch managements

► Wider frequency irrigation (with 30 mm depth) is most beneficial for tomato crop. ► Difference between SET , against maximum WUE and yield, narrowed down under mulches. ► Black polyethylene mulch can be a good option under water scarce situation. During the winter season (November–March) of 2003–2004 and 2004–2005 a field study was carried out at the Research Farm of the University (Latitude 22°58′N, Longitude 88°31′E and altitude 9.75 m amsl), Gayeshpur, India. Aim of the study was to evaluate the sole and interactive effect of irrigation frequencies and mulches on performance and water productivity functions of tomato crop. The experiment was composed of three irrigation frequencies {rainfed (RF); CPE 50 and CPE 25 where irrigation was given at 50 and 25 mm of cumulative pan evaporation (CPE)}, kept in the main plots. The subplots consisted of four mulch managements {no mulch (NM), rice straw mulch (RSM), white polyethylene mulch (WPM) and black polyethylene mulch (BPM)}. Fruit yield under CPE 25 was 39.4 Mg ha −1 ; it reduced by 7 and 30% respectively under CPE 50 and RF condition. Different mulches increased fruit yield by 23–57% over non-mulch condition. Irrespective of mulching, water use efficiency (WUE), net evapotranspiration use efficiency (WUE ET ) and irrigation use efficiency (WUE I ) were found to be the highest (22 kg m −3 , 71 kg m −3 and 22 kg m −3 respectively) under moderately wet (CPE 50 ) soil environment. Among different mulches, BPM recorded the highest WUE (25 kg m −3 ), WUE ET (73 kg m −3 ) and WUE I (26 kg m −3 ) values. Critical values of seasonal evapotranspiration (SET) against maximum WUE and maximum yield were computed through marginal analysis of water productivity function. It was observed that the difference between these critical values was narrowed down under bio or polyethylene mulches compared to the bare situation.

A Simulated Study on the Effects of Seasonal Drought on Growth and Yield of Double Cropping Rice in Hunan Province

Seasonal drought is one of the most serious disasters in rice production in Hunan Province of China.On the basis of calibration and validation of rice model ORYZA2000,the characteristics of seasonal drought and its effect on growth and yield of double cropping rice under three types of water management with continued flooding (CF),alternative wet and dry (AWD),and rainfed (RF) conditions were simulated and analyzed with history weather data from 1960 to 2007.The results were as follows,(1) The soil seasonal drought of double rice gradually occurred from panicle initiation (PI) under AWD and RF conditions,and got more serious in the process of growth,especially under rainfed condition.The late rice tended to be more easily affected by seasonal drought than early rice,and the seasonal drought was more serious at late stage than early stage.The effect of drought on biomass and yield of rice was the severest at flowering stage.The characteristics between soil drought and crop drought showed differently.(2) There appeared seasonal drought for both early and late rice under the year types of normal and dry.The drought was serious for early rice from early PI to maturity under dry year type,and its strength and duration surpassed that of normal year type.The frequency and strength of drought for late rice excessed that of early rice under dry year type,especially from PI to maturity.(3) The seasonal drought caused different losses of yield in double rice.Higher yield of rice occurred under AWD,while the lowest yield occurred under RF.The yield of late rice was lower than that of early rice under rainfed condition.This quantitative study could provide a theoretical basis for the disaster mitigation of seasonal drought and sustainable water management in double rice production in Hunan.

Effect of mulch and irrigation practices on soil water, soil temperature and the grain yield of maize (Zea mays L) in Loess Plateau, China

Agricultural management practices, such as mulching and irrigation can change the characteristics of the soil surface and hence influence the hydrothermal properties of the soil. A two-year field experiment was conducted at the Changwu agro-ecosystem research station to evaluate the effects of mulch and irrigation practices on moisture and temperature in the upper layers of the soil and on crop growth and yield performance in spring maize (Zea mays L) fields. Four mulching and irrigation treatments were examined: supplementary irrigation (SI), film mulching (FM), straw mulching (SM; in 2008 only) and a rain-fed (RF) control. The soil water (0 - 15 cm depth range) and soil temperature (0 - 5 cm depth range) were studied during the crop growing season and the treatments' yield performances were compared. Over the whole season, the average topsoil water content was significantly higher (P < 0.05) under the SM (23.3% in 2008), SI (21.4% in 2007, 22.5% in 2008) and FM (20.0% in 2007, 21.6% in 2008) treatments than under RF (17.1% in 2007, 19.6% in 2008). The seasonal trends in atmospheric and soil temperatures were similar under all treatments. The seasonally-averaged soil temperature at 07:00 and 14:00 h was highest under the FM treatment and lowest under the SM treatment. Plant height and leaf and stem biomass were significantly higher (P < 0.05) under the SI treatment than under the RF and FM treatments from silking to physiological maturity. Both the FM and SI treatments significantly improved (P < 0.05) the crop grain yield (GY) and yield components. Key words: Loess Plateau, soil water, soil temperature, spring maize.

Evaluation of resistance in wheat against Rhopalosiphumpadi (L.) (Homoptera:Aphididae) Under laboratory Conditions

AbstractAims and introduction All over the world aphids are pests of economic importance, affecting all varieties of plants like cereal crops, vegetables, ornamental plants and fruits. Aphids damage plants either directly or indirectly. Aphids are one of the major agricultural pests. There are only a few plants that are not susceptible to infestation by this destructive pest. They cause direct damage by sucking the sap of leaves, blocking photosynthesis which results in leaf distortion, gall production, discoloration, stunting, leaf curling, wilting, twisting and premature leaf falls. They are directly involved in transmission of plant viruses and indirectly by depositing honey dew that reduces photosynthetic activity and induces sooty mold production and premature leaf senescence.Methodology Hosts were wheat and maize. There was twenty varieties of National Uniform Wheat Yield Trials (NUWYT) Normal (N) of year 2004-05, and twelve varieties of (NUWYT) Rain Fed (R.F) of year 2004-05 while there were twenty-two varieties of maize of year 2005-06. All these varieties were evaluated against bird cherry oat aphid R. padi L pest. Evaluation for resistance was done by seedling bulk test and by comparing the results of components of resistance like antibiosis, antixenosis and tolerance tests. These experiments were performed under controlled environmental conditions. Experiments were of randomized complete design and replicated. The data obtained was statistically analyzed of variance (ANOVA) and the mean values were compared by Duncan’s new multiple range test (DMRT) at 5 percent level of significance (Steel and Torrie, 1980). Results Among the tested germplasm (one variety and 11 lines of wheat), the V-5 line was found resistant and the NRL-2017 line was found susceptible to Rhopalosiphum padi. The results of the Antixenosis Test indicated that two wheat lines, V-5 and PR-83 were least preferred and three lines viz., NRL-2017, V-00055 and V-00BT004 were highly preferred by the test insect. The results of the Antibiosis Test showed that PR-83 line was least fecund whereas NR-241 and V-00055 lines were highly fecund. The results of the Tolerance Test indicated that four varieties, PR-83, V-5, SN-128 and NR-241 were highly tolerant, while only one line, V-00BT004 was least tolerant. Conclusion To avoid harmful effects of this insect pest, only resistant, least preferred, least fecund and highly tolerant lines must be used in wheat breeding programs.

Evaluation of resistance in wheat against Rhopalosiphumpadi (L.) (Homoptera:Aphididae) Under laboratory Conditions

Aims and introduction All over the world aphids are pests of economic importance, affecting all varieties of plants like cereal crops, vegetables, ornamental plants and fruits. Aphids damage plants either directly or indirectly. Aphids are one of the major agricultural pests. There are only a few plants that are not susceptible to infestation by this destructive pest. They cause direct damage by sucking the sap of leaves, blocking photosynthesis which results in leaf distortion, gall production, discoloration, stunting, leaf curling, wilting, twisting and premature leaf falls. They are directly involved in transmission of plant viruses and indirectly by depositing honey dew that reduces photosynthetic activity and induces sooty mold production and premature leaf senescence.Methodology Hosts were wheat and maize. There was twenty varieties of National Uniform Wheat Yield Trials (NUWYT) Normal (N) of year 2004-05, and twelve varieties of (NUWYT) Rain Fed (R.F) of year 2004-05 while there were twenty-two varieties of maize of year 2005-06. All these varieties were evaluated against bird cherry oat aphid R. padi L pest. Evaluation for resistance was done by seedling bulk test and by comparing the results of components of resistance like antibiosis, antixenosis and tolerance tests. These experiments were performed under controlled environmental conditions. Experiments were of randomized complete design and replicated. The data obtained was statistically analyzed of variance (ANOVA) and the mean values were compared by Duncan’s new multiple range test (DMRT) at 5 percent level of significance (Steel and Torrie, 1980).ResultsAmong the tested germplasm (one variety and 11 lines of wheat), the V-5 line was found resistant and the NRL-2017 line was found susceptible to Rhopalosiphum padi. The results of the Antixenosis Test indicated that two wheat lines, V-5 and PR-83 were least preferred and three lines viz., NRL-2017, V-00055 and V-00BT004 were highly preferred by the test insect. The results of the Antibiosis Test showed that PR-83 line was least fecund whereas NR-241 and V-00055 lines were highly fecund. The results of the Tolerance Test indicated that four varieties, PR-83, V-5, SN-128 and NR-241 were highly tolerant, while only one line, V-00BT004 was least tolerant.ConclusionTo avoid harmful effects of this insect pest, only resistant, least preferred, least fecund and highly tolerant lines must be used in wheat breeding programs.

EFFECT OF DIFFERENT IRRIGATION REGIMES ON OLIVE TREE (OLEA EUROPAEA L., 'KORONEIKI') PHYSIOLOGY, YIELD AND FRUIT QUALITY

The effect of different irrigation regimes on physiological parameters (photosynthesis, leaf water potential, stomatal conductance), yield, and fruit quality, was studied in an experimental orchard planted with 50-year-old trees of cultivar 'Koroneiki' in Chania, Crete, Greece. Four treatments were applied as follows: a) fully irrigated trees (FI); b) trees irrigated at 70% ETc (crop evapotranspiration) (DI70); c) trees irrigated at 40% Etc (DI40); and d) rainfed (RF). Irrigation was applied through a drip system, and the seasonal amounts totaled 272, 189 and 108 mm of irrigation water for treatments FI, DI70 and DI40 respectively (May through September), during a year with a typical dry spell of more than 100 days. Leaf water potential was measured between 9:00 and 10:30 AM and ranged from -2.4 to -2.7 MPa for treatments FI and DI70, and from -3.2 to -3.6 for DI40, while in the RF treatment a gradual reduction from -2.5 to -6.3 MPa was observed from the beginning to the end of the dry period. During the dry season, photosynthesis was reduced to 31% and 72% in treatments DI40 and RF respectively, as compared to treatments DI70 and FI. Similarly, fruit yield was reduced by 16.6% and 32% for treatments DI40 and RF, while there was no differentiation between the DI70 and FI treatments. Oil content percentage was increased during maturation in all treatments, with lower values appearing in non-irrigated trees. Olive oil quality parameters (acidity, peroxide value, resistance to oxidation) were not affected significantly by the treatments, with the exception of total phenols, which were lower in oil produced by FI trees. In conclusion, the physiological parameters and the fruit yield were not affected by the application of a deficit irrigation regime of DI70 as compared to FI trees, while both treatments were clearly rated better, compared to the low irrigation regimes (RF and DI40).

Role of irrigation and mulch on yield, evapotranspiration rate and water use pattern of tomato (Lycopersicon esculentum L.)

▶ Two irrigations under CPE 50 resulted 9 Mg ha −1 yield increment compare to rainfed condition. The same was 12 Mg ha −1 more under five irrigations treatment. Thus, additional three irrigations amounting 90 mm enhanced the yield by only 3 Mg ha −1 . Therefore under limited water, irrigation application with moderate (CPE 50 ) level is highly desirable instead of high frequency (CPE 25 ) irrigation. Under such cases the additional three irrigations can be employed to bring out more (1.5 times) land under irrigation with 52 Mg ha −1 more yield. ▶ Among different mulches, RSM and WPM significantly increase yield to the tune of around 7 Mg ha −1 compare to NM condition. On the other hand black polythene mulch has the capacity to increase fruit yield by 16 Mg ha −1 in expense of less water compare to NM condition. So BPM could be a good management option for tomato cultivation in the Lower Gangetic Plain of eastern India. ▶ There was a close interaction between irrigation frequency and actual evapotranspiration rate (ET R ). Thus, interval between two consecutive irrigations greatly influenced the ET R value. Increase in irrigation frequency promoted more unproductive loss of water by surface evaporation. The same was decreased with the decrease in frequency of irrigation. Maximum ET rate occur under bare soil condition, which minimized by different mulches in the order of RSM > BPM > WPM. ▶ The highest WUE value (21.6 kg m −3 ) was noted when two irrigations was applied (CPE 50 ) and the same was at the lowest point when five irrigations were supplied to the crop. Among different mulches the values were in the order of BPM > RSM > WPM > NM. ▶ Finally it can be concluded that, under water scarce situation adoption of deficit irrigation clubbed with black polyethylene mulch can be a good option for utilizing water resource most efficiently without significant decrease in yield. Irrigation management strategy invites the quantification of crop response to irrigation frequencies. Conventionally, mulches increase the yield and water use efficiency (WUE) to a great extent by augmenting the water status in the root zone profile. A field study was carried out during the winter season (November–March) of 2003–2004 and 2004–2005 at the Central Research Farm of Bidhan Chandra Krishi Viswavidyalaya (Latitude 22°58′N, Longitude 88°31′E and altitude 9.75 m amsl), Gayeshpur, India, to evaluate the effect of irrigation frequencies and mulches on evapotranspiration rate from tomato crop field as well as leaf area index (LAI), fruit yield and WUE of the crop. The experiment was laid out in a split-plot design where three irrigation treatments {rainfed (RF); CPE 50 and CPE 25 where irrigation was given at 50 and 25 mm of cumulative pan evaporation (CPE)} were kept in the main plots and the subplots contained four mulch managements {no mulch (NM), rice straw mulch (RSM), white polyethylene mulch (WPM) and black polyethylene mulch (BPM)}. Under CPE 25 , tomato crop recorded significantly higher leaf area index (LAI) over CPE 50 and rainfed condition. LAI value under BPM was 9–30% more over other mulches. Maximum variation of LAI among different treatments was recorded at 60 days after transplanting (DAT). Fruit yield under CPE 25 was 39.4 Mg ha −1 ; a reduction of 7 and 30% has been obtained under CPE 50 and RF condition. The use of mulch increased 23–57% yield in comparison to NM condition. Actual evapotranspiration rate (ET R ) was 1.82 mm day −1 under CPE 25 and declined by 15 and 31% under CPE 50 and RF condition, respectively. The variation of ET R among different mulches became more prominent under maximum water stressed (RF) condition, whereas the variation was negligible under CPE 25 frequency. Irrespective of mulching WUE was highest under moderately wet (CPE 50 ) soil environment. Among different mulches, BPM was responsible for attaining the highest WUE value (25.1 kg m −3 ), which declined by 22, 21 and 39% under WPM, RSM and NM, respectively.

Stress Effects of Simulated Acid Rain on Photosynthetic Characteristics and Yield of Field-grown Spring Wheat at the Filling Stage in Semi Arid Rain Feed Region

In order to investigate the effect of acid rain on photosynthetic characteristics of spring wheat,spring wheat at the filling stage was sprayed with simulated acid rain at different pH level of 1.5,2.5,3.5,4.5 and 5.6,and then,the yield and the photosynthetic parameters of spring wheat leaves were monitored.The results indicated:①The net photosynthetic rate reduces in the range of 9.61% to 61.50%,stomatal conductance reduces in the range of 7.03% to 57.46%,transpiration rate reduces in the range of 3.70% to 55.44%,intercellular CO2 concentration increases in the range of 27.91% to 43.74%,the chlorophyll relative content reduces in the range of 12.12% to 41.92%,the yield of spring wheat reduces in the range of 15.50% to 37.05%.Effect of simulated acid rain on photosynthetic characteristics of spring wheat leaves increases more and more remarkable with the increase of hydrogen ion concentration.②The pH values of simulated acid rain was significantly positively correlated with net photosynthetic rate,transpiration rate,stomatal conductance,the relative chlorophyll content and the yield,and the pH values of simulated acid rain was significantly negatively correlated with intercellular CO2 concentration.

Response of soybean genotypes to different irrigation regimes in a humid region of the southeastern USA

Studies on irrigation scheduling for soybean have demonstrated that avoiding irrigation during the vegetative growth stages could result in yields as high as those obtained if the crop was fully irrigated during the entire growing season. This could ultimately also lead to an improvement of the irrigation water use efficiency. The objective of this study was to determine the effect of different irrigation regimes (IRs) on growth and yield of four soybean genotypes and to determine their irrigation water use efficiency. A field experiment consisting of three IR using a lateral move sprinkler system and four soybean genotypes was conducted at the Bledsoe Research Farm of The University of Georgia, USA. The irrigation treatments consisted of full season irrigated (FSI), start irrigation at flowering (SIF), and rainfed (RFD); the soybean genotypes represented maturity groups (MGs) V, VI, VII, and VIII. A completely randomized block design in a split-plot array with four replicates was used with IR as the main treatment and the soybean MGs as the sub-treatment. Weather variables and soil moisture were recorded with an automatic weather station located nearby, while rainfall and irrigation amounts were recorded with rain gauges located in the experimental field. Samplings for growth analysis of the plant and its components as well as leaf area index (LAI) and canopy height were obtained every 12 days. The irrigation water use efficiency (IWUE) or ratio of the difference between irrigated and rainfed yield to the amount of irrigation water applied was estimated. The results showed significant differences (P < 0.05) between IR for dry matter of the plant and its components, canopy height, and maximum leaf area index as well as significant differences (P < 0.05) between MGs due to IR. Differences for the interaction between IR and MG were significant (P < 0.05) only for dry matter of pods and seed yield. In general, seed yield increased at a rate of 7.20 kg for each mm of total water received (rainfall + irrigation) by the crop. Within IR, significant differences (P < 0.05) on IWUE were found between maturity groups with values as low as 0.55 kg m-3 for MG V and as high as 1.14 kg m-3 for MG VI for the FSI treatment and values as low as 0.48 kg m-3 for maturity group V and as high as 1.02 kg m-3 for maturity group VI for the SIF treatment. We also found that there were genotypic differences with respect to their efficiency to use water, stressing the importance of cultivar selection as a key strategy for achieving optimum yields with reduced use of water in supplemental irrigation

Soil water dynamics and water use efficiency in spring maize (Zea mays L.) fields subjected to different water management practices on the Loess Plateau, China

Soil water supply is the main limiting factor to crop production across the Loess Plateau, China. A 2-year field experiment was conducted at the Changwu agro-ecosystem research station to evaluate various water management practices for achieving favorable grain yield (GY) with high water use efficiency (WUE) of spring maize (Zea mays L.). Four practices were examined: a rain-fed (RF) system as the control; supplementary irrigation (SI); film mulching (FM); and straw mulching (SM) (in 2008 only). The soil profile water storage (W) and the crop evapotranspiration (ET) levels were studied during the maize growing season, and the GY as well as the WUE were also compared. The results showed that mean soil water storage in the top 200 cm of the profile was significantly (P < 0.05) increased in the SI (380 mm in 2007, 411 mm in 2008) and SM (414 mm in 2008) compared to the FM (361 mm in 2007, 381 mm in 2008) and RF (360 mm in 2007, 384 mm in 2008) treatments. The soil water content was lower at the end of growing season than before planting in the 60–140 cm part of the profile in both the RF and FM treatments. Cumulative ET and average crop coefficiency (Kc) throughout the whole maize growing season were significantly (P < 0.05) higher in the SI (ET, 501 mm in 2007, 431 mm in 2008; Kc, 1.0 in 2007, 0.9 in 2008) treatment than in the other treatments. Both FM and SI significantly improved the GY. The WUE were increased significantly (23–25%; P < 0.05) under the FM treatment. It was concluded that both SI and FM are beneficial for improving the yield of spring maize on the Loess Plateau. However, FM is preferable because of the shortage of available water in the area.

Assessment of AquaCrop, CropSyst, and WOFOST Models in the Simulation of Sunflower Growth under Different Water Regimes

This work compares the performance of AquaCrop, a crop simulation model developed by FAO, with that of two well established models, CropSyst and WOFOST, in simulating sunflower (Helianthus annuus L.) growth under different water regimes in a Mediterranean environment. The models differ in the level of complexity describing crop development, in the main growth modules driving the simulation of biomass growth, and in the number of input parameters. AquaCrop is exclusively based on the water‐driven growth module, in that transpiration is converted into biomass through a water productivity (WP) parameter; Cropsyst is based on both water and radiation driven modules, while WOFOST simulates crop growth using a carbon driven approach and fraction of intercepted radiation. The data used in the analysis were obtained in field experiments with hybrid Sanbro_MR, performed in a typical Mediterranean area of Southern Italy in 2005 and 2007. The models were calibrated on data from a full irrigation treatment in 2007, and were validated on a full irrigation treatment in 2005 and several deficit irrigation (DI) treatments, including regulated deficit irrigation (RDI) and rain‐fed (RF) conditions. Although AquaCrop required less input information than CropSyst and WOFOST, it performed similarly to them in simulating both biomass and yield at harvesting. The use of different numbers of parameters and crop growth modules by the tested models did not influence substantially the simulation results. Therefore, for management purposes and in conditions of limited input information, the use of simpler models should be encouraged.

Efeito da prática continuada do regadio sobre o complexo de troca do solo

Being the main goal of this work the analysis of the changes in the soil exchange complex brought by the continued irrigation practice, we collect georeferenciatilly, in the 12400 ha constituting the Caia Irrigation Perimeter and adjacent areas (located in the Elvas and Campo Major region, Portalegre district, Portugal), 14280 topsoil samples (020 cm), which, after mixed 10 by 10, in a way that each aggregate sample represented 11.1 ha, were analyzed for soil exchange complex composition and for soil exchange capacity (CEC). With the use of appropriate software (Geographic Information Systems-GIS), it was possible to relate the results of individual samples analysed with the cultural system (rain feed, less than 15 years in irrigation, between 15 and 25 years in irrigation and more than 25 years in irrigation) and the soil group (Regosols, Cambisols, Vertisols, Calcisols, Luvisols and Fluvisols), and then analyze the influence of the cultural system in the soil exchange complex and how the different soil groups were influenced by irrigation. With the Vertisols exception, the results confirm a decline in soil exchange capacity, sum of bases and base saturation ratio values and an increase in the exchange sodium percentage, which tends to get worse over time, at least in the first 30 years of this practice.

Monitoring the impacts of urbanization and industrialization on the agricultural land and environment of the Torbali, Izmir region, Turkey

The aim of this research is to determine agricultural land loss and environmental pollution caused by industrialization and urban sprawl using the Geographical Information System (GIS) and Remote Sensing technique (RS). Remotely sensed data is the most powerful tool for monitoring land use changes and GIS is the best way to store and reproduce various kinds of integrated data. Considering the rapid increase of population the loss of fertile agricultural soils is a very dangerous situation for the future of the country. Thus, people are living in the cities in (with adverse) conditions of insufficient drinking water, infrastructure problems, inadequate landscape and many unsolved (extreme) environmental problems. During the last 36 years, unplanned urbanization and industrialization have led to the use of agricultural areas for non-agricultural purposes in the Torbali (Izmir) region, which has the most fertile soils of the Aegean Region. Within this study, a database was created on the parameters of land loss and environmental pollution by means of field observation, interpretation of satellite images (ASTER), aerial photos(1/25.000 scale), topographic map, soil map, and 1/5.000 scale cadastral map. Results of previous researches and the archives of Torbali municipality were used as ancillary data. In the research, urbanization and industrialization of the town was studied by (using) GIS and RS between 1965 and 2001. Since 1965, 4,742,357 m2 agricultural land, mostly of first and second land use capability classes, has been lost due to unplanned urban and industrial developments. Urbanization and industrialization involved an area of which 58% was being used as irrigated lands, 25 % rain feed (rain fed lands)and 17 % for olive growing.

Exploring options for water savings in lowland rice using a modelling approach

Water-saving irrigation regimes are needed to deal with a reduced availability of water for rice production. Two important water-saving technologies at field scale are alternately submerged–nonsubmerged (SNS) and flush irrigated (FI) rice. SNS allows dry periods between submerged soil conditions, whereas FI resembles the irrigation regime of an upland crop. The effects of these regimes on the water balance and water savings were compared with continuously submerged (CS) and rainfed (RF) regimes. The crop growth model ORYZA2000 was used to calculate seasonal water balances of CS, SNS, FI, and RF regimes for two locations: Tuanlin in Hubei province in China from 1999 to 2002 during summer seasons and Los Baños in the Philippines in 2002–2003 during dry seasons. The model was first parameterized for site-specific soil conditions and cultivar traits and then evaluated using a combination of statistical and visual comparisons of observed and simulated variables. ORYZA2000 accurately simulated the crop variables leaf area index, biomass, and yield, and the soil water balance variables field water level and soil water tension in the root zone. Next, a scenario study was done to analyse the effect of water regime, soil permeability, and groundwater table depth on irrigation requirement and associated rice yield. For this study historical weather data for both sites were used. Within seasons, the amount of irrigation water application was higher for CS than for any of the water-saving regimes. It was found that groundwater table depth strongly affected the water-yield relationship for the water-saving regimes. Rainfed rice did not lead to significant yield reductions at Tuanlin as long as the groundwater table depth was less than 20 cm. Simulations at Los Baños with a more drought tolerant cultivar showed that FI resulted in higher yields than RF thereby requiring only 420 mm of irrigation. The soil type determined the irrigation water requirement in CS and SNS regimes. A more permeable soil requires around 2000 mm of irrigation water whereas less permeable, heavy soil types require less than half of this amount. We conclude that water savings can be considerable when water regimes are adapted to soil characteristics and rainfall dynamics. To further optimize water-saving regimes in lowland rice, groundwater table dynamics and soil permeability should be taken into account.

Assessment of solar radiation models and temporal averaging schemes in predicting radiation and cotton production in the southern United States

Crop models require daily weather input data for solar radiation (I rad), minimum and maximum air temperatures, precipitation, and windspeed; but measured I rad may not be available at some locations, necessitating I rad estimates. A total of 28 scenarios (7 solar radiation models (SRMs) × 4 temporal-averaging schemes (TASs)) were examined to estimate I rad and cotton (Gossypium hirsu- tum L.) yield at 10 U.S. locations. The SRMs showed positive correlations of I rad with daylength and temperature range (Tmax - Tmin), and were relatively accurate in predicting I rad and yield. The I rad esti- mation accuracy depended on SRM, TAS, and location. Temporal averaging smoothed out short-term fluctuations, resulting in decreased temporal scatter in the weather parameters. The combination of Tmin, Tmax, precipitation and wind (TmRnWn) model performed best, and I rad estimation accuracy was highest in Shafter, California, and Maricopa, Arizona. Highest I rad estimation accuracy was obtained with the TmRnWn model, using a double TAS, in Maricopa (r 2 = 0.99). Geographical variability in I rad was observed, showing effects of regional climate on measured I rad and on I rad estimation accuracy. Yield estimation accuracy depended on I rad estimation accuracy and yield response to I rad changes, and depended more strongly on location and management practice (rainfed (RF) versus irrigated (IRR)) than on SRM and TAS. All 7 SRMs performed comparably well in predicting RF and IRR yields. Estimation accuracies for I rad and RF + IRR cotton yields among the 28 scenarios were highest for Shafter and Maricopa (e.g. r 2 > 0.99 for yield). Coupled with crop simulation models, SRMs are use- ful for predicting I rad and crop yields, particularly in regions with unavailable measured I rad data.

Irrigation and Polymer Effects on Herbicide Transport through the Unsaturated Zone of a Sparta Sand

AbstractState‐sponsored monitoring programs show that the Sparta sand (sandy, mixed, mesic Entic Hapludoll) of the Lower Wisconsin River Valley (LWRV) is susceptible to herbicide movement through the vadose zone, especially atrazine [2‐chloro‐(4‐ethylamino)‐6‐(isopropylamino)‐s‐triazine]. Experiments were initiated to examine the effect of irrigation scheduling and pesticide formulation on transport through the vadose zone. Intact Sparta sand (SP) columns were extracted from the LWRV and instrumented to simulate temperature, irrigation and drainage conditions encountered in the field. Labeled 14C‐atrazine, alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl) acetamide], and metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1‐methylethyl) acetamide] were monitored in the leachate. Treatments included irrigation schedules to match no‐irrigation or rainfed (RF), evapotranspiration (ET) and ET plus an additional 25% (ET +). Formulation treatments consisted of standard pesticide tank‐mix mixtures with and without the addition of a polymer (2% by volume). Increased water input significantly increased metolachlor transport through the SP profile. Due to variability in the leachate data, no significant differences in the total amount of atrazine leached through the columns were shown to exist between the ET and ET + treatments; however, after initial irrigation, atrazine concentration in leachate from ET + treatment was 10 to 15 times greater than leachate of the ET treatment. When compared to the standard herbicide formulation, the use of the polymer significantly reduced and delayed the peak concentrations of metolachlor in the leachate. A significant difference also was observed in the amount of metolachlor retained in the surface soil (0–10 cm) of those columns receiving the polymer treatment compared to those receiving the standard application of the herbicide.

Evaluation of Peanut Genotypes for Resistance to Water Stress In Situ1

Observations indicate that Spanish‐type peanuts (Arachis hypogaea L.) are more tolerant of dehydration than Virginia types under severe water stress. However, physiological reasons for differences in tolerance to water deficits among peanut genotypes have not been established. The objective of this study was to evaluate peanut genotypes for their response and relative resistance to severe water deficits. A Spanish type (‘Comet’), Virginia type (‘Florunner’), and a Spanish ✕ Virginia selection (OK‐FH15) were grown in situ under irrigated (IRR) and rainfed (RF) conditions. Leaf water potential (ψw), osmotic potential (ψπ), turgor potential (ψp), relative water content (RWC) and its apoplastic water fraction (Aw) were determined weekly between 1300 and 1500 h, and diurnally on selected days. Yields were determined at 149 days after planting (DAP). Ratios (RF/IRR) genotype ψw, ψπ, and RWC showed significant differences among genotypes between 50 and 63 DAP, a critical period of peanut growth and development. The ψw and RWC ratios were maximum for all genotypes at 63 and 70 DAP, respectively. The maximum ψπ ratio occurred on 56 DAP for Comet (1.25), 63 DAP for OK‐FH15 (1.32), and 70 DAP for Florunner (1.18). Regression analysis of 1/ψw vs. RWC showed a biphasic cubic polynomial function best fit the data for all genotypes. The data indicated that as RWC declined, Comet ψw tended to decrease more rapidly than either OK‐FH15 or Florunner. Conservative estimates of ψπ, changes between 95 and 55%R WC were highest for Comet, lowest for Florunner, and OK‐FH15 was intermediate. Aw was calculated for each genotype and plotted against ψp to determine its contribution to hydration maintenance. At high ψp, maximum Aw, was 7.1, 12.1, and 25.2%f or Florunner, OK‐FH15, and Comet, respectively. Florunner Aw, decreased to zero at 0.16 MPa ψp, and the Aw of OK‐FH15 decreased with ψp to the origin. Comet had much greater Aw at low ψp and was the only genotype with appreciable Aw at zero ψp. These results indicate that Aw varies in peanuts and may be genotype specific. Comet showed significantly higher yield, grade, and dollar value than either Florunner or OK‐FH15 under rainfed conditions. The lower ψw, greater change in ψπ, and higher Aw and yield of RF Comet suggests greater resistance to dehydration when high soil moisture deficits and evaporative demand conditions occur.