Water use,growth and rubber yields of four guayule selections as related to irrigation regimes

Summary There has been renewed interest in cultivating guayule (Parthenium argentatum G.) for rubber production. Water use, growth and rubber yields of four guayule selections (593, 11.591, 11 646 and 4265 XF) were evaluated for two years in nonweighing field lysimeters at El Paso, TX. Four irrigation treatments were evaluated; these involved irrigation when about 40, 60 or 90% of available water was depleted, and the fourth treatment was irrigated at 60% depletion using saline water containing 3,300 mg of dissolved salts per liter. Water use for the two year period for these treatments amounted to 219, 147, 96 and 132 cm, respectively, plus biennial rainfall of 32 cm. Shrub and resin yields increased linearly with increasing irrigation, while rubber contents generally decreased with irrigation. Resultant rubber yields were highest under the lowest stress treatment, yielding about 840 kg/ha. Rubber yields with other treatments averaged 560 kg/ha with no significant yield differences among the tested selections. The salt treatment increased rubber contents of the shrubs, but caused reductions in shrub and rubber yields. Guayule plants survived well under low soil moisture, but water requirement to produce unit quantities of biomass was high (about 15 cm to produce one ton of dry shrub per ha). Guayule should not be regarded as a low water consuming crop if high yields per land area are to be achieved.Contribution from Texas Agricultural Experiment Station. This project was supported in part by a fund from USDA Latex Commission and Binational Agricultural Research and Development Fund (BARD). The authors are Associate Professor, and Technicians, respectively     

新疆博河及精河流域水资源评价与水质分析

河流在地区农业发展、区域供水、保持生态平衡中起着重要作用,而由于各地经济、人口规模的不断增加,水资源需求量猛增,加上工业活动范围的逐步扩大,很多流域出现供水不足、水质污染等问题,严重制约了可持续发展.本文以新疆博河及精河流域为研究对象,通过水均衡法评价分析了流域内水资源的开发利用现状.同时,运用综合水质标识法对流域水质进行了分析.     

Effect of irrigation method and quantity on squash yield and quality

Squash yield and quality under furrow and trickle irrigation methods and their responses to different irrigation quantities were evaluated in 2010 spring and fall growing seasons. A field experiment was conducted using squash (Cucurbita pepo L.) grown in northern Egypt at Shibin El Kom, Menofia. A randomized split-plot design was used with irrigation methods as main plots and different irrigation quantities randomly distributed within either furrow or trickle irrigation methods. Irrigation quantity was a fraction of crop evapotranspiration (ET_c) as: 0.5, 0.75, 1.0, 1.25, and 1.5 ET_c. Each treatment was repeated three times, two of five rows from each replicate were left for squash seed production. In well-watered conditions (1.0 ET_c), seasonal water use by squash was 304 and 344 mm over 93 days in spring and 238 and 272 mm over 101 days in fall under trickle and furrow irrigation methods, respectively. Squash fruit yield and quality were significantly affected by season and both irrigation method and quantity. Fruit number and length were not affected by irrigation method and growing season, respectively. Interaction between season and irrigation quantity significantly affected leaf area index, total soluble solid (TSS), and fruit weight. Moreover, seed yield and quality were significantly affected by growing season and both irrigation method and quantity except harvest index, which was not affected by irrigation method. Significant differences for the interaction between season and irrigation method were only found for seed yield and 100 seeds weight. Except for harvest index, no significant difference was observed by interaction between season and irrigation quantity. Both fruit and seed yields were significantly affected in a linear relationship (r² ≥ 0.91) by either deficit or surplus irrigation quantities under both irrigation methods. Adequate irrigation quantity under trickle irrigation, relative to that of furrow, enhanced squash yield and improved its quality in both growing seasons. Fall growing season was not appropriate for seed production due to obtaining many of empty seeds caused by low weather variables at the end of the season. The results from small experiment were extrapolated to large field to find out optimal irrigation scheduling under non-uniform of irrigation application.     

水资源水质水量优化配置分析

本研究旨在实现水资源水质水量的优化配置,通过对水资源水质水量优化配置的生态经济学理论进行分析,指出水资源水质水量优化配置的概念,在内涵分析基础上确定了水资源水质水量优化配置的具体阈值原理和模型体系框架.同时对青海水资源水质水量的优化配置进行分析,指出不同区域的水资源水质水量需要进行针对性的优化配置.     

Application of the Soil and Water Assessment Tool (SWAT) to predict the impact of alternative management practices on water quality and quantity

Alternative land management practices such as conservation or no-tillage, contour farming, terraces, and buffer strips are increasingly used to reduce nonpoint source and water pollution resulting from agricultural activities. Models are useful tools to investigate effects of such management practice alternatives on the watershed level. However, there is a lack of knowledge about the sensitivity of such models to parameters used to represent these conservation practices. Knowledge about the sensitivity to these parameters would help models better simulate the effects of land management. Hence, this paper presents in the first step a sensitivity analysis for conservation management parameters (specifically tillage depth, mechanical soil mixing efficiency, biological soil mixing efficiency, curve number, Manning's roughness coefficient for overland flow, USLE support practice factor, and filter strip width) in the Soil and Water Assessment Tool (SWAT). With this analysis we aimed to improve model parameterisation and calibration efficiency. In contrast to less sensitive parameters such as tillage depth and mixing efficiency we parameterised sensitive parameters such as curve number values in detail.In the second step the analysis consisted of varying management practices (conventional tillage, conservation tillage, and no-tillage) for different crops (spring barley, winter barley, and sugar beet) and varying operation dates. Results showed that the model is very sensitive to applied crop rotations and in some cases even to small variations of management practices. But the different settings do not have the same sensitivity. Duration of vegetation period and soil cover over time was most sensitive followed by soil cover characteristics of applied crops.     

Water quality assessment of different reservoir types in relation to nutrient solution use in hydroponics

Hydroponics requires good quality water. For this purpose, water quality is based on concentrations of specific ions and phytotoxic substances as well as the presence of organisms and substances that can clog irrigation systems. Here, four irrigation reservoirs, i.e. two rainwater ponds, a peat ditch, and a natural lake, were analyzed to determine whether or not they conform to water quality guidelines. Based on our data, the four reservoirs could be divided into two categories in respect to their water quality. The two rainwater ponds belong to the category characterized by low input of ionic strength (480 μmol m⁻¹), low concentration of unwanted ions, such as SO₄²⁻ (63 μmol l⁻¹) and Zn²⁺ (3.9 μmol l⁻¹), a moderate bacterial population (lg 4.9 CFU m⁻¹), and moderate algae density (lg 6.0 cells ml⁻¹). The rainwater ponds were found to contain a good diversity in bacteria (45 species from 25 genera), and a poor diversity of algae (15 species from 4 groups). The other category, to which the peat ditch and natural lake belong, is characterized by a high ionic strength (12,200 μmol l⁻¹), high concentrations of alkali ions (Mg²⁺: 890 μmol l⁻¹; Ca²⁺: 3.260 μmol l⁻¹; K⁺: 470 μmol l⁻¹), a moderate bacterial (lg 4.7 CFU ml⁻¹), but low algae density (lg 5.0 cells ml⁻¹). In comparison to the first category, the diversity of the bacteria was poor (seven species from three genera). However, in sharp contrast was the rich algal community detected in the peat ditch, for which 32 species from six groups were found, whereas in the natural lake, only one group with seven species was identified. In all reservoirs, species of the genera Paenibacillus and Bacillus were detected, and small green algae, e.g. Scenedesmus spp., also dominated in each case. Overall, the bacterial and algal densities showed wide fluctuations between water sources, and neither caused filter clogging as observed in investigations of others. The quality of the rainwater investigated was assessed to be well suited for use in hydroponics due to appropriate nutrient concentration (except Zn²⁺ in one pond), and lack of potential bacterial and algal development. However, we recommend water from the natural lake and the peat ditch to be used with care because of the high nutrient concentration.     

农业水利灌溉现状及节水措施

我国作为农业生产大国,在农业生产的同时也要考虑水资源的节约与合理利用。论述了农业水利灌溉现状及农业节水措施。      

稻米品质及其评定

随着人们生活水平的不断提高,对食用稻米品质的要求也越来越高。稻米品质是稻米在商品流通中所具有的基本特征,如何客观地、科学地评价稻米品质,已日趋重要。     

Water requirements of subsurface drip-irrigated faba bean in California

A 3-year study was done in central California to determine the water requirements for growing faba bean (Vicia faba L.) as a winter cover crop using subsurface drip irrigation (SDI). Water was applied at 0, 50, and 100% of the estimated crop evapotranspiration (ET_c) the first 2 years and 50, 100, and 150% ET_c the third year, with drip laterals installed 0.30, 0.45, or 0.60 m deep. Rainfall was above normal the first year (>330 mm) and irrigation had no effect on crop production. Irrigation improved production and water-use efficiency the following years, however. Production was higher when drip laterals were located at 0.30 or 0.45 m than at 0.60 m depth, even though roots tended to be concentrated near the laterals (later in the season) regardless of depth. Overall, well-irrigated faba bean required 231-297 mm of water to produce 3.0-4.4 t ha^у of dry vegetative biomass.     

Water and leaching requirements of industrial tomatoes irrigated with brackish water

Summary The objective of the study was to examine the production functions of industrial tomatoes (Lycopersicon esculentum cv. M-82) with saline and nonsaline water and to determine their water and leaching requirements. The experiment was conducted in small field plots on a sandy loam soil. Water was applied by drip irrigation at three different salinity levels (EC_i) in amounts ranging from about 30 to 120% of the optimum with nonsaline water.Contribution from the Agricultural Research Organization, No. 1439-E 1984 series     

Water requirements of olive orchards: I simulation of daily evapotranspiration for scenario analysis

Water requirements of olive orchards are difficult to calculate, since they are influenced by heterogeneous factors such as age, planting density and irrigation systems. Here we propose a model of olive water requirements, capable of separately calculating transpiration (E _p), intercepted rainfall evaporation (E _pd) and soil evaporation (E _s) from the wet and dry fraction of the soil surface under localized irrigation. The model accounts for the effects of canopy dimension on E _p and of the wetted soil surface fraction on E _s. The model was tested against actual measurements of olive evapotranspiration (ET) obtained by the eddy covariance technique in a developing olive orchard during 3 years. The predicted ET and crop coefficients showed good agreement with the measured data. The model was then used to simulate the average water requirements of two mature orchards using 20-year meteorological datasets of Cordoba (Spain) and Fresno (CA, USA). Average annual ET of a 300 trees ha⁻¹ orchard at Cordoba was 1,025 mm, while the same orchard at Fresno had an average ET of 927 mm. Transpiration losses were 602 mm at Cordoba and 612 mm at Fresno. Evaporation from the soil can have a large effect on olive ET; thus, olive crop coefficients (K _c) are very sensitive to the rainfall regime.     

Salt effects on germination and seedling emergence of several vegetable crops and guayule

Summary Salt effects on seed germination and seedling emergence of several crops are evaluated to understand poor plant stands occurring in furrow-irrigated fields in saline areas. The test crops were carrot (Daucus carota L. cv. Imperator 58), chile pepper (Capsicum annuum L. cv. New Mexico 6-4), tomato (Lycopersicon esculentum M. cv. Rutgers), and guayule (Parthenium argentatum G. cv. 593). Seed germination was measured in petri-dishes containing saline solutions (0.8 to 32 dSm^–1 with a Na to Ca + Mg ratio of about 2 : 1); and seedling emergence in potted fine loamy sand subirrigated in a greenhouse with saline waters (0.8 to 7.6 dSm^–1 with SAR < 16). Seedling emergence through a thin layer of salted-loamy sand (having EC _e up to 46 dSm^–1) placed on emerging seedlings was also evaluated. Germination of tomato and carrot seeds began to decline at solution salinities of 12 and 18 dSm^–1, respectively, and was virtually zero at 23 dSm^–1, Chile pepper and guayule germinated well at 23 dSm^–1, Tomato had the highest emergence, and guayule the lowest, showing less than 20% when subirrigated at 2.2 dSm^–1, Seedling emergence which increased in the order of guayule, carrot, chile pepper and tomatoes did not quantitatively correlate with seed germination. However, it did correlate with the emergence through the thin layer of the salted-sand placed over emerging seedlings except in tomato. Salinity of the saturation extract of the surface 5 mm soil increased to 21 and 31 dSm^–1, in 7 days when subirrigated with water of 4.3 and 6.4 dSm^–1, respectively. Poor seedling emergence of guayule, carrots and, to some extent, chile pepper appeared to be caused by hypocotyl mortality associated with the salts accumulated at the soil surface, but not by reduced seed germination. The control of surface accumulated salts should be the target of management for improved emergence of these crops.Contribution from Texas Agric. Exp. Station. This project was supported in part by a grant from Binational Agricultural Research and Development (BARD) fund, the Expanded Research fund and the Latex Grant, USDA     

Salt effects on transplant mortality,growth and rubber yields of guayule

Summary Because of the strategic and industrial importance of natural rubber, there has been renewed interest in cultivating guayule (Parthenium argentatum). This study was performed for assessing feasibility of guayule cultivation with waters high in dissolved salts. The test materials included six USDA selections (11591, 11605, 11619, 11646, 12229 and N576), one cultivar (593) and one hybrid (4265XF). Seedlings were grown for l0 weeks in a greenhouse and transplanted in the spring and in the summer into lysimeters (unit surface dimension of 6 x 7 m) containing loamy sand or silt loam. They were grown with simulated irrigation waters having four levels of salinity (0.8, 2.4, 4.6 and 7.2 dSm^–1 with SAR < 13) and an additional water containing 5 mmol L^–1 of Mg at 2.4 dSm^–1. In the spring planting, over 90% of the transplants survived when furrow irrigated weekly with waters of 4.6 dSm^–1 or less. However, transplant growth for the first several months was reduced by half at irrigation water salinity of 4.6 dSm^–1. In the summer planting, several fold increases in mortality and growth reduction occurred. Dry top Shrub yields after the two growing seasons following the spring planting averaged 10 Mg ha^–1 at 0.8 dSm^–1 and declined on the average 15 and 51 % when irrigated with waters of 4.6 and 7.2 dSm^–1 respectively. The amount of water used to produce one ton of dry shrub was 1,600 m³ with waters of 0.8 and 4.6 dSm^–1, and 1,900 m³ with water of 7.2 dSm^–1. The contents of rubber in the shrubs averaged 61 g kg^–1 at 0.8 dSm^–1 and increased to 70 g kg^–1 at 7.2 dSm^–1. whereas resin contents were not affected by the salt treatments. Resulting rubber yields were reduced on the average by 8.5 and 44% at 4.6 and 7.2 dSm^–1. respectively, because of the reduction in shrub yields. Selection N576 produced the largest rubber yields with the highest rubber content at all levels of salinity. Increasing Mg concentrations from 0.5 to 5 mmol L^–1 in the irrigation waters reduced neither yields nor transplant survival. Yield reductions observed here appeared to be related to Na, but not Mg.Contribution from Texas Agricultural Experiment Station. Supported in part by a grant from the Latex Commission, USDA and by the US-Israel Binational Agricultural Research and Development (BARD) fund     

Water requirements of olive orchards–II: determination of crop coefficients for irrigation scheduling

Intensification of olive cultivation by shifting a tree crop that was traditionally rain fed to irrigated conditions, calls for improved knowledge of tree water requirements as an input for precise irrigation scheduling. Because olive is an evergreen tree crop grown in areas of substantial rainfall, the estimation of crop evapotranspiration (ET) of orchards that vary widely in canopy cover, should be preferably partitioned into its evaporation and transpiration components. A simple, functional method to estimate olive ET using crop coefficients (K _c=ET/ET₀) based on a minimum of parameters is preferred for practical purposes. We developed functional relationships for calculating the crop coefficient, K _c, for a given month of the year in any type of olive orchard, and thus its water requirements once the reference ET (ET₀) is known. The method calculates the monthly K _c as the sum of four components: tree transpiration (K _p), direct evaporation of the water intercepted by the canopy (K _pd), evaporation from the soil (K _s1) and evaporation from the areas wetted by the emitters (K _s2). The expression used to calculate K _p requires knowledge of tree density and canopy volume. Other parameters needed for the calculation of the K _c’s include the ET₀, the fraction of the soil surface wetted by the emitters and irrigation interval. The functional equations for K _p, K _pd, K _s1 and K _s2 were fitted to mean monthly values obtained by averaging 20-year outputs of the daily time step model of Testi et al. (this issue), that was used to simulate 124 different orchard scenarios.     

Water requirements of young coconut palms in a humid tropical climate

Summary The evapotranspiration rates of five-year-old coconut palms (Cocos nucifera Linn. cv West Coast Tall) grown in an Oxisol on the West coast of India were quantified from soil moisture depletion studies and lysimetric measurements. The rates increased from 2.9 mm day^–1 in December to 5.5 mm day^–1 in April and reduced to 2.3 mm day^–1 in June following the onset of monsoon rain. Ratios of evatranspiration to class A pan evaporation were 0.87–0.88 in the moderate rainfall period (September and October), 0.78–0.85 in the winter period (November–February), 0.87–0.96 in the summer period (March–May) and 0.60–0.68 in the rainy period (June–August).     

我国水资源现状与节水农业发展探讨

我国是世界上水资源严重紧缺的国家之一,干旱缺水已成为威胁粮食安全、制约农业可持续发展的主要限制因素.分析我国水资源现状和促进节水农业发展的经济意义,指出我国节水农业发展中存在的问题,并提出具体措施,以促进对水资源的保护与合理利用.     

Water quality in drip/trickle irrigation: A review

Summary The intensive treatment of irrigation water required for the proper operation of drip irrigation systems is presently an accepted practice. To control emitter clogging, we need to know the basic causes of clogging. The major clogging factors have been identified and control measures developed to prevent emitter malfunction. All emitter clogging problems, however, have not been solved primarily because of cost. The main approach to control clogging is proper water treatment. The type of treatment is based on the quality of the irrigation water, which can be classified in terms of its physical, chemical and biological composition. The causes of emitter clogging and possible water treatment and preventive measures to maintain reliable operation are reviewed.     

海伦市用水现状与2020年需水预测

【目的】预测城市的生活、工业、农业用水的需水,对城市的规划、经济发展以及供水系统的管理及扩建提供可靠依据。【方法】使用水平衡分析法及线性回归分析和大量的数据运算,通过线性回归分析现状年及2013—2017年用水量分析了海伦市用水现状并预测了2020年需水量。【结果】2020年海伦市城镇居民生活用水为774.66万m~3,农村居民生活用水量为1 622.32万m~3,2020年海伦市工业需水量为0.061亿m~3,2020年海伦市农业需水总量为3.64亿m~3。【结论】预测年2020年供水量大于需水量。