Moisture Tension Research Articles

Performance of Dry-Seeded Rice Genotypes under Varied Soil Moisture Regimes and Foliar-Applied Hormones.

Plant hormones influence various physiological processes during the growth and development of plants, but their critical roles in influencing yield and antioxidant activities in dry-seeded rice (DSR) have not been adequately explored. This study aims to analyze the performance and antioxidant activity of contrasting genotypes of DSR in response to soil moisture regimes and foliar-applied hormones. The study comprised sixteen treatments that were evaluated under field conditions as per split-plot design in three replications. Treatments comprised combinations of two soil moisture tension regimes (10 kPa and 20 kPa) and two genotypes (PR-111, non-stay-green type and PR-123, stay-green type) applied to the main plots and foliar application of three hormones (gibberellic acid (GA3) 40 mg kg−1, abscisic acid (ABA) 20 mg kg−1, and cytokinin (CK) 40 mg kg−1)) and a control (unsprayed) to subplots. The non-stay-green genotype (PR-111) resulted in 34.6% more grain yield (6.48 t ha−1) than the stay-green genotype (PR-123) at the lower soil moisture tension regime (SMTR) (10 kPa) due to the increased number of filled grains per panicle and improvement in harvest index (HI). At the higher SMTR (20 kPa), the stay-green genotype (PR-123) produced 26.4% more grain yield (5.21 t ha−1) than non-stay green genotype (4.12 t ha−1) and showed enhanced superoxide dismutase (SOD) and peroxide dismutase (POD) activity that may have contributed in maintaining sink size through improved chlorophyll content. Grain yield (6.35 t ha−1) with foliar-applied GA3 (40 mg kg−1) at SMTR of 10 kPa was higher by 12.2% and 24.0% than with foliar-applied ABA (20 mg kg−1) and unsprayed treatments, respectively. Irrigation application at SMTR of 20 kPa and foliar application of ABA gave 24.1% higher grain yield (5.15 t ha−1) than the unsprayed treatment, but it was similar to foliar-applied GA3 and CK. This study implied that the stay-green genotype (PR-123) was more suitable under moisture stress conditions (20 kPa) in DSR, as it maintained sink size even under moisture stress conditions by improving dry matter translocation and enhancing SOD and POD activity. The study suggests the need to find out the endogenous level of these plant hormones in rice genotypes under a range of water regimes to develop high yielding and water use efficient genotypes of DSR.

Moisture tension in fine-grained reconstituted soils at high initial water contents

The reclamation of land filled with high water content dredged clays is an important geological and geo-environmental issue. When designing such reclaimed land, the yield behaviour during compression is of paramount importance because it conditions the compressibility of soil and thus the final ground settlement. Previous studies suggest a significant effect of initial state of soils on their compression behaviour; in particular, the remoulded yield stress (identified when compressing reconstituted samples at high initial water content) decreased with the increase in initial water content. This phenomenon has been attributed to the effect of moisture tension. In fact, for a reconstituted soil at high initial water content, non-destroyed aggregates may exist in microscopic level although the degree of saturation of soil reaches 100% in macroscopic level. These aggregates can give rise to the generation of negative water pressure inside the aggregates, namely moisture tension. This moisture tension can greatly affect the mechanical behaviour of soil in the macroscopic level. With the destruction of aggregates, the moisture tension decreases. In order to verify this surmise, a series of experiments were conducted with moisture tension measurement on reconstituted Jossigny silt at three different water contents (1.0, 1.2 and 1.5 times the liquid limit). Meanwhile, mercury intrusion porosimetry (MIP) tests were conducted to analyse the macroscopic features. The test results proved the existence of moisture tension, and it decreased with increasing water content. When the aggregates are destructed completely, the moisture tension becomes zero. The non-intruded void ratio obtained from MIP tests was found to increase with decreasing water content, suggesting the destruction of aggregates by further hydration. Physically, the moisture tension corresponds to the water absorption potential of aggregates or the potential changes of aggregates from metastable state to true stable state. These observations provide experimental evidence supporting the existence of the remoulded yield stress identified for saturated reconstituted soils.

Plant Available Water Capacity (PAWC) for Deep-Rooted Crops in Cracking Clay Soils (Vertisols) of Semi-Arid Central India

Smectite is the dominant clay mineral in the cracking clay soils (mainly Vertisols) in the semi-arid tropical (SAT) region (Vidarbha andMarathwada).Amongst the crystalline clay minerals, smectite has the highest soil moisture retention capacity depicted as the available water between field capacity and wilting point, which increases with soil depth. But in SAT Vertisols of Vidarbha and Marathwada regions, the release of this soil water is unavailable to deep-rooted crops, causing loss of crop yield is frequently observed. Thus, the water holding between33 and 1500 kPa tension is not in reality available soil moisture in these soils. The release of soil moisture is, however, seriously constrained by the dispersion of smectitic clay colloids due to the presence of both Mg and Na ions on soil exchange complex. In reality, in calcareous Vertisols of non-sodic nature, soil moisture is held at 100 kPa while in calcareous Vertisols of sodic nature it is held at 300 kPa. Based on this field observation the concept of plant available water content, which relates to profile water content, was adopted earlier to calculate the plant available water capacity (PAWC) considering the soil moisture held between 100-1500 kPa for non-sodic and 300-1500 kPa for sodic soils. This pragmatic PA WC method showed a significant positive correlation between the PA WC and the yield of cotton (lint + seed) of 32 Vertisols of the Vidarbha region, however, it did not address the status of soil moisture release at higher tensions. It is apprehended that at higher tensions, the release of soil moisture is not enough during the dry period of the season that can prevent the extension of vertical cracks in the slickensided horizons at deeper depth of 100 cm and beyond. Less amount of soil water in the subsoils is due to the decrease of saturated hydraulic conductivity(sHC) with depth preventing the free flow of rainwater in the subsoils. This makes subsoils as more water constraint horizons but enriches subsoils with pH > 8.0, more amount of Mg2+ and Na+ ions on soil exchange complex. Such Vertisols do not support the second crop during the winter months. In view of this predicament in agricultural land use plan of SAT Vertisols, the present study was undertaken to understand the cause and effect relationship between soil moisture and relevant soil parameters that prevent the release of soil moisture at higher tensions. In order to find an insight into this queer issue, soil moisture retention and release curves at 33, 100, 300, 500, 800, 1000 and 1500 kPa, were obtained for each genetic horizon of 33 representative Vertisols ofVidarbha andMarathwada region. In Vidarbha, Vertisols are Aridic/Typic/Sodic Haplusterts and Calciusterts, and in Marathwada, they are Typic/Sodic Haplusterts. Moisture tension curves indicate that the release of water beyond 800 kPa is negligible. Failure in the release of soil water beyond 800 kPa is due to the dispersion of fine clay size smectite (< 200 nm) consisting primarily of nano-size smectite (<100 nm), caused by the Mg2+ and Na+ ions present on the soil exchange complex. The dispersed nano-size smectite blocks the macropores and simultaneously increase the micropores, where soil moisture is held very tightly. In the present study, PA WC calculation was done considering the soil water held between 100-800 kPa for soils of non-sodic nature, and for sodic soils, it was between 300-800 kPa. The revised PAWC data showed a better significant positive correlation with yields of cotton on farmers ’field, in comparison to correlation obtained earlier. Thus, it stands as a robust index parameter of soil abiotic stress in SAT environment. This unique parameter having a legacy to major pedogenetic processes in SAT Vertisols. In Indian states under SAT, PAWC emerges as a formidable biophysical parameter for evaluation of rain-fed Vertisols for growing deep-rooted crops.

Determinación de los requerimientos de riego por aspersión en el cultivo de la achira (Canna edulis) y la influencia en sus etapas fenológicas

La achira (Canna edulis) con su principal derivado, el almidón, es muy apetecido y cotizado, en la elaboración de productos enlatados, en las industrias farmacéutica, textil, de papelería y adhesivos; y, en uso medicinal. Es una especie de gran importancia para la economía de las familias campesinas del sector sur oriental del cantón Loja (Ecuador). En cuanto a su cultivo aún se desconocen los elementos básicos necesarios que permitan hacer una planificación en zonas irrigadas. Por lo antes mencionado, se planteó la presente investigación denominada: "Determinación de los requerimientos de riego por aspersión en el cultivo de la achira (Canna edulis) y la influencia en sus etapas fenológicas en la provincia de Loja" El objetivo general fue determinar los requerimientos hídricos de la achira, a través del análisis de la evapotranspiración de referencia y del cultivo, y de la determinación del coeficiente del cultivo, mediante la utilización de riego por aspersión. Se aprovechó la presente investigación para conocer la influencia de las dosis de agua de riego entregada al cultivo y su rendimiento en almidón; la proyección hecha para una hectárea determinó que cuando se regó con tensiones de 40 centibares se obtuvo 8412,11 kg/ha (185 quintales/ha); con tensiones 30 cbar se logró 8157,03 kg/ha (179,45 quintales/ha); y, con tensiones de 20 cbar se consiguió 7653,91 kg/ha (168,39 quintales/ha). Se comprobó que la mejor tensión de humedad para utilizar en el cultivo de achira fue la de 40 centibares al haber alcanzado el mayor rendimiento de 8412,11 kg/ha (185,0 quintales/ha); y mayor concentración de almidón (14,61%).

Experimental Investigation of Lateral Subsurface Flow Depending on Land Use and Soil Cultivation

The magnitude and timing of flood events are influenced by surface and subsurface flow generation as well as by present land use distribution. An integrated understanding of the interactions of soil properties, land use and flow generation is still missing. Therefore, field experiments are required to gain further knowledge about land use dependencies of discharge generation and concentration processes. In our research, we built an experimental setup consisting of three sites with similar soil and topographic conditions and different land use types (cropland, grassland, forest). The applied multimethod approach includes meteorological parameters, soil moisture, soil moisture tension, surface runoff, lateral subsurface flow, and stream discharge observations. The results show that low subsurface flow discharges more often occur at the cropland site, while large flow volumes were mainly observed at the grassland site. A correlation of the horizontal distribution of subsurface flow volumes and the accumulation areas of the surface topography has been found (r² = 0.76). The observed average response times for advective events increase from the forest site (6.0 h) to the grassland site (12.4 h) to the cropland site (20.9 h). Response times of convective events were shorter than 1 h at all sites.

Computed tomography as an extension of classical methods in the analysis of soil compaction, exemplified on samples from two tillage treatments and at two moisture tensions

Some soil physical properties can easily be measured using classical laboratory methods. However, explicit valuable information on the real morphology of the pore structure as well as soil physical properties cannot be obtained at the same time with classical methods. This requires non-destructive measurements such as X-ray computed tomography (CT).However, explicit valuable information on the real morphology of the pore structure as well as soil physical properties cannot be obtained at the same time with classical methods.This paper combines parameters obtained from CT analysis (mean macropore diameter, macroporosity, pore connectivity, anisotropy) and classical laboratory methods (dry bulk and aggregate density, saturated hydraulic conductivity, mechanical precompression stress) to analyse soil compaction, exemplified on samples from two tillage treatments (cultivator and plough) and at two moisture states (6 and 1000 kPa matric potential) on a Chernozem collected at a soil depth of 16–22 cm (texture 0–30 cm: silty clay loam).The study shows that the matric potential can have a decisive impact on the mechanical stability of soil. In the loose but less stable plough treatment a more negative matric potential was clearly beneficial to the mechanical stability. In already dense soil structures, as in the cultivator treatment, a reduction of water content was less effective in increasing soil stability.The CT parameters were all closely and uniquely related to each other. The shown CT parameters can be used for a standardized characterization of the soil. Ploughing has a positive effect on soil structure which persists only as long as macroporosity and mean macropore diameter remain high. Plough maintains higher pore connectivity when compacted under dry conditions.

Earthworm activity and availability for meadow birds is restricted in intensively managed grasslands

Abstract Earthworms are an important prey for the endangered meadow birds of northwest Europe. Although intensive grassland management with high manure inputs generally promotes earthworm abundance, it may reduce the effective food availability for meadow birds through desiccation of the topsoil, which causes earthworms to remain deeper in the soil. We studied the response of Red Worm Lumbricus rubellus, a detritivore, and Grey Worm Aporrectodea caliginosa, a geophage, to soil moisture profiles in the field and under experimental conditions. Surfacing earthworms were counted weekly in eight intensively managed grasslands (treated with high inputs of slurry by slit injection) with variable groundwater tables in the Netherlands. At each count, soil penetration resistance, soil moisture tension and groundwater level were measured, while air temperature and humidity were obtained from a nearby weather station. The response to variation in the vertical distribution of soil moisture was also experimentally studied in the two earthworm species. In the field, earthworms’ surfacing activity at night was negatively associated with soil moisture tension and positively by relative air humidity. Surprisingly, there was no effect of groundwater level; an important management variable in meadow bird conservation. Under experimental conditions, both L. rubellus and A. caliginosa moved to deeper soil layers (&gt;20 cm) in drier soil moisture treatments, avoiding the upper layer when moisture levels dropped below 30%. Synthesis and applications. We propose that in intensively managed grasslands with slurry application, topsoil desiccation reduces earthworm availability for meadow birds. This can be counteracted by keeping soil moisture tensions of the top soil above −15 kPa. We suggest that the late raising of groundwater tables in spring and the disturbance of the soil by slit injection of slurry increase topsoil desiccation. This decreases earthworm availability when it matters most for breeding meadow birds. Meadow bird conservation will benefit from revised manure application strategies that promote earthworm activity near or at the soil surface.

Multispectral satellite imagery to quantify in-field soil moisture variability

As pressure on available water resources increases, the need to exploit technology in order to produce more food with less water becomes crucial. The technological hardware requisite for precise water delivery methods, such as variable rate irrigation, is commercially available. Despite that, techniques to formulate a timely, accurate prescription for those systems are inadequate. Spectral vegetation indices are often used to gauge crop vigor and related parameters (e.g., leaf nitrogen [N] content). However, research heretofore rarely addresses the influence of soil moisture on the indices. The objectives of this study were to determine (1) if vegetation indices derived from multispectral satellite imagery could assist in quantifying soil moisture variability in irrigated maize (<i>Zea mays</i> L.) production, and (2) the period of time that a single image is representative of soil moisture. A variable rate irrigation pivot was used to form six water treatment zones. Each was equipped with tensiometers installed in the center of the plots at 20, 45, and 75 cm depths to individually monitor conditions in the water treatment zones. Water was applied for each treatment as a percentage of the estimated evapotranspiration (ET) requirement: 40%, 60%, 80%, 100%, 120%, and 140%. Data collected from tensiometers was paired with the image pixels corresponding to its ground location. Statistical analysis was performed separately to assess whether vegetation indices are representative of soil moisture at several crop growth stages. Findings from this study indicate that Red Edge Normalized Difference Vegetation Index could quantify soil moisture tension variability at V6 (six leaf; <i>r</i>² = 0.850, <i>p</i> = 0.009) and V9 (nine leaf; <i>r</i>² = 0.913, <i>p</i> = 0.003) crop growth stages. Results suggest that satellite-derived vegetation indices may be useful for creating time-sensitive characterizations of soil moisture variability. Further study is necessary to investigate additional crop growth stages, more crops, and other sources of multispectral imagery.

Monitoring the performance of urban green infrastructure using a tensiometer approach

Little is known about how stormwater exfiltrates from green infrastructure and few efforts have been undertaken to address this question. This study used tensiometers to monitor water exfiltration from an aggregate-filled storage gallery installed under permeable pavement. An 80-space parking lot was built at Seitz elementary school in Fort Riley, KS under an agreement between EPA and US Army during the summer of 2015. A network of twelve tensiometers and twelve monitoring wells was installed under and south of the storage gallery. Tensiometers were installed a various depths and distances to monitor soil moisture tension. The installation was used to monitor subsurface water flow patterns from the storage gallery under the permeable pavement site. The results of the study showed that soil moisture tension is larger at the shallower depths, decreasing with depth from the ground surface. Larger soil tension was associated with increased distance from the permeable pavement storage gallery. The results showed exfiltration from both the sidewalls and the bottom of the gallery while the changes in soil tension were larger for the tensiometer monitoring exfiltration from the side walls. Both the accumulated water depth inside the storage gallery and groundwater level rise were positively correlated with total rainfall depth. The calculated vertical flow rate was larger than the horizontal flow. The soil water tension change associated with storage gallery exfiltration was measured in a radius of <5 m from the storage gallery. Long-term peak groundwater level rise should be considered for design of the storage gallery depth to maintain the effective exfiltration. Understanding the exfiltration pathways aids with the placement and design the storage gallery. Additional research is necessary to understand how specific local parameters and vadose zone characteristics would affect the long-term exfiltration process.

Comparing a Smartphone Irrigation Scheduling Application with Water Balance and Soil Moisture-based Irrigation Methods: Part I—Plasticulture-grown Tomato

A new smartphone vegetable irrigation scheduling application (VegApp) was compared with current irrigation scheduling recommendations and soil moisture sensor (SMS)–based irrigation for growing tomato (Solanum lycopersicum) in southern Georgia during Spring 2016 and 2017. Plants were grown using plastic mulch and drip irrigation following standard production. The VegApp-scheduled irrigation based on crop evapotranspiration (ETc) values calculated daily from meteorological data retrieved from nearby weather stations, whereas ETc rates for current water balance (WB)–based recommendations were calculated from historic averages for the region. Water usage, soil moisture tension, fruit yield and quality, and foliar macronutrient content were measured. In 2016, plants grown using SMS-based irrigation applied the least water followed by the VegApp- and WB-grown plants. In 2017, WB-treated plants received the least water, followed by VegApp- and SMS-grown plants. Total marketable yields were similar among treatments and years. Irrigation water use efficiency (IWUE) varied between year and irrigation regime, with SMS-grown plants having a significantly greater IWUE than the other treatments in 2016. Plants irrigated using the VegApp had a greater IWUE than SMS-irrigated plants in 2017. Differences in IWUE were largely the result of variable irrigation volumes and not changes in yield. Fruit total soluble solids (TSS) were unaffected by treatment in either study year. Fruit pH was affected by irrigation treatment in 2017. Foliar nitrogen concentrations were affected by irrigation regime in 2017, with VegApp-grown plants having significantly greater concentrations of foliar N than other irrigation treatments. The results of this study suggest that the VegApp could be a reliable tool that can be used by growers to produce yields comparable to currently accepted irrigation scheduling practices and reduce water use in some seasons.

Soil moisture tension as an alternative for improving sustainable use of irrigation water for habanero chilies (Capsicum chinense Jacq.)

During 2015 and 2016, two experiments were conducted under contrasting climatic conditions (rainy and dry seasons, respectively) in Campeche, Mexico, to test various thresholds (treatments) of soil moisture tension for the beginning of irrigation, and their effect on the yield and quality of Habanero Chilies, and also on the efficiency of water use, the virtual water content and its blue and green components. In both experiments, irrigation was initiated when the soil moisture tension, measured at 30 cm depth, took the values −10, −40 and −70 kPa, considered as treatments, using producer irrigation management as a control. The number of fruits per plant (NFP), fruit weight per plant (FWP), fruit diameter (FD), fruit length (FL), yield (Y), total water use efficiency (TWUE), irrigation water use efficiency (IWUE), virtual water (VW), green virtual water (GVW), and blue virtual water (BVW) were determined and statistically analyzed. During 2015, rains masked treatment effects, although significant effects were detected for FL, IWUE, VW and BVW. In 2016, the different irrigation treatments during the dry season had significant effects on the variables NFP, FWP and Y, with statistically higher values in the −10 kPa treatment; and also in IWUE, GVW and BVW with statistically higher values in the −70 kPa, −40 kPa and the control treatments, respectively. Nearly all crop growth and yield related variables had higher values with lower soil moisture tension. In both production cycles, significantly lowest values for IWUE and significantly highest values for BVW were obtained under producer irrigation management (controls); whereas significantly highest values were recorded for IWUE and significantly lowest for BVW in the −40 and −70 kPa treatments. It was concluded that the use of tensiometers to define the beginning of irrigation allows for improving irrigation sustainability.

Preliminary Variations in Physiological Modules When &amp;lt;i&amp;gt;sub&amp;lt;/i&amp;gt;1&amp;lt;i&amp;gt;A&amp;lt;/i&amp;gt; QTL Is under Soil-Moisture Deficit Stress

The present investigation embodies with some distinct physiological responses of rice seedlings bearing sub1A allele when cultured under soil moisture deficit condition. In order to estimate the extent of variation of sub1A allele in cv. Swarna Sub1, few specific responses were recorded. Ongoing days (2, 4 and 8) of water stress, rice seedlings were mostly concerned with regulation of root growth through 1.24%, 4.10% and 8.96% as compared to control. When relative growth rate (RGR) of the biomass was considered, it recorded a significant down regulation maximum by 27.27% over non-stressed plants. The light absorbing capacity of foliages in terms of leaf mass ratio (15.62%) and specific leaf weight (8.45%) was also curtailed under stress contiguously with total dry matter accumulation. For light harnessing mechanism, the contributing pigments were most significantly (p ≤ 0.05) affected with maximum variation for chlorophyll (31.29%), lycopene (79.31%) and carotenoids (55.31%) over control. NAR was strikingly differed by 32.72% under water stress in average. To support the water stress related depletion of moisture tension, plants recorded RWC with a ranges of 6.62% to 21.57% under stress than control. In balance of cellular dehydration rice seedlings were recorded 6.72% loss of proline, but up-regulated the release of free amino acids by 1.35 fold. In expression of generic potential for sub1A allele, the growth inhibition even under water deficit was evident from carbohydrate depletion by 10.93%, 11.42% and 24.35% through days of treatments. This was supported by depletion of apoplastic and cellular invertase activities by 90.90% and 72.91%. The possibility for sub1A in tolerance of deficit water status in rice culture has been discussed in more details.

Infrared thermometry to quantify in-field soil moisture variability

ABSTRACTTechniques to formulate accurate and timely prescriptions for variable-rate irrigation systems lag behind the hardware capabilities. Canopy temperature measurements could serve as an indicator of water stress, but current methods that exploit the data can be cumbersome. The objectives of this study were 1) to determine the relationship between synchronous measurements of maize (Zea mays L.) canopy temperature and in-field soil moisture tension, and 2) to understand the influence of discretionary crop canopy temperature stress thresholds on the relationship between soil moisture tension and crop canopy temperature. A variable-rate irrigation pivot was used to form six water-treatment zones. Each zone was equipped with tensiometers installed in the center of the plots and an infrared thermometer pointed into the crop canopy to individually monitor conditions in each zone. Results of this study indicate that synchronous canopy temperature was able to quantify soil moisture tension, particularly during the reproductive crop growth stages. Using inexpensive infrared thermometers with this method could provide a cost-effective solution for gauging in-field soil moisture variability.

Enhancing irrigation water productivity in paddy grown under sodic environment

Paddy being one of the most important food crop in India covering about one-fourth of the total cropped area and providing food to about half of the Indian population. About 50 per cent of rice crop in India is raised under irrigation; this requires application of either surface or groundwater in rice fields. This paper addresses the water management strategies of rice crops under sodic environment, as under sodic environment during monsoon season rice is the sole option. Sodic soils are characterized by a relatively low electrical conductivity (EC), high exchangeable sodium (Na) on exchange sites, soil pH > 8.0, low rate of infiltration, and dispersed soil, restricting capacity of these soils to absorb desired water and poor infiltration characteristics. To address these challenges, an experiment was conducted to determine the suitable irrigation strategy by varying irrigation depth and irrigation interval. Two depth of irrigation 5 cm and 7 cm along with irrigation schedule of 2, 3 and 5 days of disappearance of ponded water and when soil moisture tension reaches at 7.5 kPa and 10 kPa were opted besides one control plot where depth of irrigation was 7.5 cm and irrigation was applied when hair cracks were visible in the rice fields. The results revealed that higher depth of irrigation and shorter irrigation interval is not resulting saving of irrigation water as irrigation schedule of 2-DAD (applying 7 cm irrigation depth) using about 4 percent higher irrigation water to result only 7 percent higher yield over control. Whereas, irrigation strategy of 3day and 5-day interval (applying 5 cm irrigation depth) resulting 40 to 50 percent of water saving and 12 to 14 percent higher yield over control plots. Hence, use of 5 cm depth of irrigation at 3 to 5 days after dissapearnce of ponded water in rice field may result in considerable water saving without compromising yield.

Irrigation management of greenhouse zucchini with different soil matric potential level. Agronomic and environmental effects

Greenhouse horticultural crops are characterized by high levels of efficiency and productivity of irrigation water. But they still can and must be improved, especially in arid areas. The objective of this research was to study the effect of the soil matric potential level on the bio-productivity of zucchini crop, the water use efficiency (WUE) and nutrients use efficiency by changing the threshold of soil matric potential. An experiment was conducted in greenhouse-grown zucchini on a sand-mulched soil and fertigation with inorganic fertilizer. Automatic activation of irrigation through an electronic tensiometer and three treatments were applied: Activation of irrigation to −10kPa and application of volume of 1.5Lm−2 (T1), activation of irrigation to −25kPa and application of volume of 2.0Lm−2 (T2) and activation of irrigation to −40kPa and application of volume of 3.0Lm−2 (T3). Yield, leaf area, biomass, water consumption, WUE and nutrients, drainage volume and physical-chemical parameters of the soil were determined. The results show that T2 slightly reduced the weight of the fruit with respect to T1, but not the number of fruit, obtaining a significantly lower consumption of water. Lower weight fruits and less number of fruits were obtained by T3. Reducing the soil moisture tension level increased substantially water consumption as a result of the differences in vegetative growth (leaf area and biomass) in plants. Highest values of WUE and nutrients use efficiency were registered by T2 and T3. In none of the treatments, drainage was obtained. Soil physical-chemical parameters were not affected by treatments. Independently of soil matric potential, increased soil salinity occurred after the growing season. The soil matric potential of −25kPa was the best considering agronomic and environmental aspects, as the most efficient use of water and nutrients obtaining a commercial production of 15kgm−2.

Soil moisture tension effect on sugar cane growth and yield

An experimental plot was established in Campeche, México, to assess the effect of moisture tension on sugarcane growth and yield. Irrigation and water efficiencies were calculated as well as the cane and sucrose virtual water contents. Three levels of soil moisture tensions (−15kPa in T1, −45kPa in T2, −75kPa in T3) were used to begin irrigation in treatments compared with a control without irrigation (T4), in an experimental randomized block design. Height and stem diameter were significantly higher (p≤0.05) in T1, treatment where also significantly higher cane and sucrose yields were observed (134.7 and 19.9tha−1, respectively). No significant differences in industrially relevant variables for the quality of sugar cane juice were found, although in T3 the highest Brix degrees and sucrose content in juice were obtained. Also in this treatment the highest irrigation water use efficiency (IWUE) was found, with an average increase in cane weight of 405kgmm−1. Overall, the IWUE and the total water use efficiencies were directly and inversely proportional to the soil moisture tension, respectively. Irrigation water applied varied from 14.0 to 19.56% of the total water depth received by the crop for treatments T3 and T2, respectively, and contributed to a gain in cane and sucrose yields of 179–252%, and from 181 to 242%, for T3 and T1 treatments, respectively. For total cane and sucrose virtual water values, a direct relationship with the soil moisture tension was found. The highest value in cane blue virtual water was found in T2 (0.0274m3kg−1) and the lower in T3 (0.0247m3kg−1). In contrast, higher values of cane green virtual water were found at higher soil moisture tensions (Control treatment, 0.271m3kg−1). Since the final sucrose yield was strongly linked to the cane yield, a very similar behavior as for cane blue and green virtual water values was observed for sucrose blue and green water contents.

Estrogenic activity in drainage water: a field study on a Swiss cattle pasture

Dairy cow manure applied to pastures is a significant potential source of estrogenic contamination in nearby streams. One possible pathway is through infiltration via preferential flow to drainage pipes, particularly after heavy rainfall events. In a period of 73 days in the spring of 2010, a drainage catchment in a cattle pasture in the Swiss lowlands was closely monitored. Manure was applied three times during the study, and part of the catchment was also subjected to grazing. During five field campaigns, water samples from two sampling locations were taken for 4–24 h in consecutive sampling intervals. 17β-estradiol equivalents (EEQ) were determined with the yeast estrogen screen (YES) and the ER-CALUX assay. Some water chemistry parameters, pH, conductivity, oxygen content and soil moisture tension were also monitored. Washout of estrogenic activity was highest during or right after heavy rainfall events, shortly after manure spreading, when peak values of >10 ng/l EEQ were found in several samples. However, in two field campaigns, high EEQ values were also found 14 and 28 days, after the last manure application, in one case during a dry weather period. This indicates that estrogenic compounds are more stable in natural soils than what is expected from data gathered in lab studies. Streams in agricultural areas with a high proportion of drained land may be subject to numerous peaks of EEQ during the course of the year. This may have a negative effect on aquatic organisms, namely fish embryos, living in these streams.

Evaluation of Four Sunflower Hybrids (Helianthus annuus) under Three Irrigation Regimes and Two Doses of Fertilization on Flower Production

Flower production is an income source for farming families. However, their productivity has been limited due to the lack of information on technical managements of crop species. In Mexico, 21,129 hectares are planted every year, with an annual production of 83,000 tons of flowers for decoration, and a total production value of 6,097 million Mexican pesos. In order to design agronomic management practices for sunflower production in the state of Campeche, three factors were evaluated: 1) sunflower hybrids, 2) time of irrigation and 3) fertilization doses, with four (hybrids: “Sunbright”, “Prado Red Shade”, “Full Sun” and “GH-382”), three (soil moisture tension at the start of irrigation of -10, -35 and -60 kPa), and two (Fertilization formulas: 60-50-0, and 30-25-0) levels, respectively using a sub split plot arrangement nested in a complete random block design with three replicates. Response variables evaluated were: plant height (PH), stem diameter (SD), leaf width (LW), leaf length (LL), distance between nodes (DN), number of inflorescences (NF), inner diameter (IDF), external diameter (EDF) and capitulum weight (CW). Irrigation affected PH, SD, LL, IDF, EDF, and CW. In all these variables, the highest values were found when irrigation was conducted at the lowest moisture tension (-10 kPa). Likewise, in all those variables significant effect of hybrids were found, which confirms that the morphology of flowers is defined by genetic factors. Specifically, hybrid “Full Sun” had significantly higher PH, SD, and DN compared to the rest of the hybrids. “Full Sun” and “Sunbright” had the highest values for PH and LL. “Full Sun” and “GH 382” had significantly higher IDF and EDF. “Prado Red Shade” had significantly lower PH, SD, LL, CW and higher NF. Fertilization only had significant effects on LW, DN and CW. In conclusion, irrigation improves morphological characteristics of sunflower plants. If the farmer’s objective is to produce larger flowers, then hybrids “Fun Sun” and “GH 382” are recommended. However, if the objective is to produce small flowers, hybrids “Sunbright” and “Prado Red Shade” are recommended. The latter is also suitable to produce a larger number of capitula.

Responses of Lactuca Sativa (Lettuce) to Fertilization Rates at Various Soil Moisture Conditions at Protected Cultivation

This research was performed to test the hypothesis that the optimal fertilization rate for lettuce is various with soil moisture conditions. The experiment was conducted under a rainfall-intercepted facility in Suwon, South Korea from 2002 to 2003. Soil was irrigated at 30, 50, or 80 kPa of soil moisture tension at 15 cm soil depth in 2002 spring and fall and 20, 30, 50, or 80 kPa in 2003 spring. Fertilization was performed with four levels in spring for both years: none, 0.5, 1.0, and 1.5 times of the recommended N, P, and K fertilization rate. The irrigation amount increased with decreased irrigation starting point as soil moisture tension. The maximum yield was found at the lowest soil moisture tension in spring while irrigation at 50 kPa resulted in the greatest yield in fall. The yield responses of lettuce to fertilization rates were various with soil moisture condition. In spring, maximum yield was found at 1.0 or 1.5 times of the recommended fertilization rate at 20, 30, and 50 kPa irrigation while 0.5 or 1.0 times of fertilization rate resulted in the maximum yield in fall. Especially for 80 kPa irrigation in 2003 spring, yield was decreased by fertilization. It suggested that the optimum fertilization rate for lettuce is affected by soil moisture condition and that lower fertilization rate should be suggested when soil is managed in drier condition.

Growth and Development of Quality Protein Maize (QPM) Genotypes As Influenced by Irrigation and Plant Population in a Sudan Savanna Ecology, Nigeria

An experiment was carried out to assess the growth and development of quality protein maize (QPM) genotypes to various plant populations under different irrigated conditions in a semi arid ecology of Northern Nigeria. Field trials were conducted at the Irrigation Research Station, Institute for Agricultural Research, Kadawa (11 o 39’ N, 08 o 20’ E) and 500 m above sea level) for three years, 2007, 2008 and 2009 during dry seasons to study the effect of three maize ( Zea mays L .) genotypes (TZE - W Pop X 1368, EV - DT W99 STR and DMR - ESRW), four plant populations (33,333, 44,444, 55,555 and 66,666 plants ha - 1 ) and three irrigation scheduling regimes (40, 60 and 80 centibars soil moisture tension) on the growth and development of QPM. This was a three trial experiment with factors arranged in a split plot design, whereby genotype and irrigation scheduling