Light-textured Soils Research Articles

Assessing agricultural land suitability in the Fakkeh region, Iran

Land suitability assessments can provide useful information to help optimize agricultural land use. Due to the current lack of appropriate land management practices in the Fakkeh region, southwest Iran, a land suitability evaluation study for key agricultural crops, including wheat, alfalfa, maize and barley, covering 43,700 ha was undertaken. Qualitative evaluation was carried out using two methods, the simple limitation and parametric methods (Storie and square root method), to compare land and climate characteristics with crop needs. The most important limiting factors in wheat, alfalfa and barley production included the physical properties of the soil, especially light soil texture. The major limiting factors in maize production were low relative humidity and high n/ N ratio during the plant growth period, light soil texture, soil salinity and alkalinity.

Range of soil and climate characteristics appropriate for Pistacia atlantica forest development and rehabilitation (case study: Fars province, Iran)

Abstract Investigation of ranges of soil and climate characteristics appropriate for the tolerant species: Pistacia atlantica subsp. mutica according to field study was the main objective of this research. This study was carried out based on random sampling across 20×20 km wild pistachio forests of Fars province (Iran). Results showed that mountainous and hilly lands are the main land types that pistachio species have evolved on. Statistical analysis of physical and chemical soil characteristics based on principal component analysis (PCA) method showed that wide ranges in soil characteristics, even up to about 40% differentiation in some measured properties, did not restricts this subspecies natural growth. The main growth limiting factors were shallow soil depth and light soil texture that decreased storage capacity of soil moisture, necessary for wild pistachios survival during drought and long dry periods. Climatic elements were analysed through the same approach and showed that temperature, precipitation and wind with overall variability of 85.9% were the most effectual factors. Pistacia atlantica subsp. mutica is one of the species refractory to various soil conditions and adapted to weak soils for the establishment and rehabilitation of forests in semi-arid regions.

Nitrate leaching in a winter wheat-summer maize rotation on a calcareous soil as affected by nitrogen and straw management

Nitrate leaching is one of the most important pathways of nitrogen (N) loss which leads to groundwater contamination or surface water eutrophication. Clarifying the rates, controlling factors and characteristics of nitrate leaching is the pre-requisite for proposing effective mitigation strategies. We investigated the effects of interactions among chemical N fertilizer, straw and manure applications on nitrogen leaching in an intensively managed calcareous Fluvo-aquic soil with winter wheat-summer maize cropping rotations on the North China Plain from October 2010 to September 2013 using ceramic suction cups and seepage water calculations based on a long-term field experiment. Annual nitrate leaching reached 38–60 kg N ha−1 from conventional N managements, but declined by 32–71% due to optimum N, compost manure or municipal waste treatments, respectively. Nitrate leaching concentrated in the summer maize season, and fewer leaching events with high amounts are the characteristics of nitrate leaching in this region. Overuse of chemical N fertilizers, high net mineralization and nitrification, together with predominance of rainfall in the summer season with light soil texture are the main controlling factors responsible for the high nitrate leaching loss in this soil-crop-climatic system.

Response of pomegranate (Punica granatum) to drip irrigation system in light textured soils of semi-arid regions

The study was designed to evaluate numbers and different arrangements of emitters under surface drip irrigation system in pomegranate (Punica granatum L.) cv. Bhagwa orchard grown on light textured soil. A field experiment was conducted at National Research Centre on Pomegranate, Solapur for three consecutive years (2010 to 2013). The treatments consisted of irrigation with 2 online emitters (8 lph) on single lateral (T1), 3 online emitters (4 lph) on single lateral (T2), 4 emitters (4 lph), 2 online, 2 through microtube on single lateral placed on four sides of plant (T3), 6 emitters (2 lph) on double laterals placed 50 cm apart on both side of plants (T4) and inline lateral having 8 emitters (2 lph) placed in the form of ring encircling the plant (T5). Experiment was laid out in randomized block design with four replications. Equal quantity of irrigation equivalent to 0.80 E. Pan was applied on every alternate day. The results revealed that irrigation with 6 emitters (2 lph) on double laterals placed 50 cm apart on both sides of plants provide higher and uniform distribution of water in the root zone of the plants, resulted in better nutrient uptake, growth and yield performance of pomegranate plants. Highest leaf content of N (2.36%) and P (0.17%) was observed in this treatment which reflected in highest increase in plant height (20.4%) and plant spread (22.7%) producing highest yield in terms of numbers (36.1) and weight (6.889 kg) of fruits/plant. Plants irrigated with inline lateral having 8 emitters (2 lph) placed in the form of ring encircling the plant recorded highest leaf chlorophyll content (57.2) and maintained cool plant canopy as indicated by lowest leaf temperature during all the fruiting months. Flowering intensity was high in the plants irrigated with 2 dripper (8 lph) on one lateral system but it does not reflected in producing fruit yield due to limited wetting zone inducing moisture stress to the plants as indicated by highest fruit cracking (11.1%) in this system. It can be concluded that irrigation with 6 emitters (2 lph) fixed on two laterals placed on both sides of plants 50 cm away from the trunk along the rows system should be provided to pomegranate grown on light textured soils of semi-arid regions.

Determining Corn Aflatoxin Risk within Counties in Southern Georgia, USA using Remotely Sensed Data

Aflatoxin contamination of food can cause liver cancer in humans and animals. Identification of aflatoxin risk areas allows farmers to adapt management strategies before planting, during growth and at harvest. Aflatoxin contamination is driven by high temperatures and drought conditions and crops grown on light textured soil in the south eastern USA are at particular risk. Aflatoxin assessment is expensive so a role of extension services in precision farming is to identify the areas most at risk of contamination so that farmers can adapt irrigation or planting strategies. This paper extends a county-level risk factors approach developed by Kerry et al. (2017) by investigating the use of NDVI and thermal IR data to indicate drought stress and thus aflatoxin contamination risk at the sub-county level.

Qualidade dos pêssegos da região da Beira Interior no ciclo 2015

In Portugal, peach production is mainly located in Beira Interior, representing 45% of the national area, corresponding to 1630 ha. The commercialization of peaches occurs between June to September and this offer is based on a wide range of cultivars. For each cultivar besides the harvest date, the fruits have different characteristics which are influenced by cultural techniques and by the soil and climate conditions. The Beira Interior region has predominantly light-textured soils and high number of light hours these conditions are favourable for stone fruit production, especially cherry and peach, which are recognized in Portugal for their quality. This study aims to characterize the fruits of the different peach cultivars produced in Beira Interior region during the 2015 season. Fruits samples from de all the cultivars produced in four local peach growers were analized. In total were analysed 1208 fruit, 47 samples corresponding to 33 different cultivars. Fruit weight firmness and total solids soluble content (SSC) was evaluated in each fruits. The titrable acidity (RTA) was evaluated for groups of 10 peaches. Based on the characteristics evaluated it has been possible to group the cultivars into three groups according the season of maturation, namely, early cultivars (9 cultivars), season cultivars (17 cultivars), and late cultivars (7 cultivars). The season cultivars have a firmness of 5.1±1.4 kg/0.5 cm2, an SSC 13.2±1.7°Brix and 5.7±2.8 g. of malic acid L‑1 and the late cultivars group has higher values of firmness, IR index and acidity, respectively 6.4±1.4 kg/0.5 cm2, 14.5±1.8°Brix and 8.6±1.5 g. of malic acid L‑1.

A Spatio–Temporal investigation of risk factors for aflatoxin contamination of corn in southern Georgia, USA using geostatistical methods

Aflatoxin is a mycotoxin produced by the Aspergillus flavus fungi that can severely contaminate corn grain. The U.S. Food and Drug Administration (FDA) have set a limit of 20 ppb, total aflatoxin, for interstate commerce of food and feed as it can induce liver cancer in humans and animals. Contamination is exacerbated by high temperatures, drought conditions and light-textured soil which are all common in Georgia (GA). Lack of irrigation infrastructure can further amplify drought stress and aflatoxin contamination. Accurate aflatoxin assessment requires the collection of multiple corn samples, is expensive and conducted at harvest which does not allow for the use of in-season mitigation strategies to reduce the risk. Given the expense of measurement and the consequences of crop loss, an important goal for agricultural extension services is the prediction and identification of years and counties at higher risk of aflatoxin contamination. This would allow growers to deploy management tactics to reduce risk and to reduce unnecessary expense on aflatoxin testing. In this research, aflatoxin levels were analysed by Poisson kriging and used to validate a strategy for identifying high risk years and counties. It is based on mapping risk factors (Maximum June temperatures, June rainfall, % corn planted area and % soil drainage types) that are above key thresholds. The aflatoxin data used were county level, collected unevenly in space and time from 1977 to 2004 in 53 counties in southern GA. Averaging and typical geostatistical methods were unreliable for producing a temporal summary of the spatial patterns because aflatoxin data were highly skewed and approached a Poisson distribution, and averages for counties with fewer observations are less reliable. Poisson kriging down-weights the influence of these in variogram computation and the estimation process. Comparison tests confirmed significant differences in aflatoxin levels between counties and years that were identified as having different levels of risk using the risk factors approach. Sensitivity analysis for Poisson kriged aflatoxin risk showed that the more years of data are clearly better for this analysis, but fewer than 15 years of data were not advisable.

Response of two-row and six-row barley to fertiliser N under Irish conditions

Abstract A range of cultivar types, including two-row and six-row types as well as line and hybrid types, are used for winter barley production in Ireland. There is little information available on the fertiliser nitrogen (N) requirements or the N use efficiency of these different types, particularly under Irish conditions. The objectives of the work presented here were to compare the response to fertiliser N of a two-row line cultivar, a six-row line cultivar and a six-row hybrid cultivar in terms of grain yield and aspects of N use efficiency. Experiments were carried out over three growing seasons, in the period 2012-2014, on a light-textured soil comparing the response of the three cultivars of winter barley to fertiliser N application rates ranging from 0 to 260 kg N/ha. There was no evidence that cultivar type, regardless of whether it was a two-row or six-row line cultivar or a six-row hybrid cultivar, influenced the response to fertiliser N of winter barley. There were some indications that six-row cultivars were less efficient at recovering soil N but used accumulated N more efficiently than the two-row cultivar. This work provided no evidence to support adjustment of fertiliser N inputs to winter barley based on cultivar type.

Effects of Sewage Sludge Amendment on Some Soil Properties, Growth, Yield and Nutrient Content of Raspberry (Rubus idaeus L.)

This study was focused not only at the assessment of effects of different sewage sludge application rates on vegetative parameters and yield of raspberry (Rubus ideaus L.) but also heavy metal accumulation in the soil and raspberry leaves. A three-year field study was set up in a completely randomized block design with five sewage sludge application rates (0.0, 2.5, 5.0, 7.5 and 10.0 kg of dry matter per plant) and three replications. One-year-old, virus free ‘Heritage’ saplings were used for the experiment. The results of this study clearly indicated that the sewage sludge application is an effective mean for improvement of vegetative growth, yield, soil and plant chemical properties of raspberry in light textured soils. In addition to macro-element contents, sewage sludge application also caused significant changes in micro-element content of soils. No adverse effects of these increases were observed on plants throughout the experimental period. The most effective application rate was found as 7.5 kg per plant for this ecological condition. It can be concluded that when properly treated and applied to farmland sewage sludge is not only disposed economically but also improved vegetative growth and yield of raspberry.

Standardization of organic manure application in pomegranate (Punica granatum) orchards grown in semi-arid regions

An experiment was conducted at ICAR - National Research Centre on Pomegranate during 2011-12 and 2012-13 on pomegranate (Punica granatum L) cv. Bhagwa plants. The experiment comprises of application of raw and well decomposed farmyard manure in the form of slurry (liquid form, manures mixed with water in 1:10 ratio and kept for 10 to 15 days with intermittent stirring) as a sole or in combination with micronutrients and/or various microbial inoculants. It was compared with normally practiced method of organic manure application in the soil. The results revealed that application of farmyard manure in slurry form decreased electrical conductivity (0.94 to 0.72 dS/m) and increased organic carbon content (0.55 to 1.45 %) in the soil. Combined application of FYM in the form of slurry along with micronutrients and microbial inoculants significantly increased available N (339.7 kg/ha) and P (34.8 kg/ha) and micronutrients content in the soil. Substantially increased plant height (20.8%), plant spread (22.8 %) and produced maximum number of fruits (39.0/ plant). Population of soil microbes, viz. Aspergillus niger, Pseudomonas fluorescence and potash solubilising organisms were significantly highest with the combined application of FYM in slurry form and microbial inoculants. While, Azotobacter population was more in raw FYM slurry along with microbial inoculants. It is recommended that on light textured soils, farmyard manures should be applied in the form of slurry. It reaches in the active root zone of the plants along with percolating water.

Improving the estimation of evaporation by the FAO-56 dual crop coefficient approach under subsurface drip irrigation

Partitioning of evapotranspiration and estimating of irrigation contribution to evaporation play a crucial role in managing scarce water resources and help in increasing the water productivity of crops, especially of sparsely vegetated plants. In this study, the FAO-56 dual crop coefficient (DCC) approach for estimating evaporation from soil under cropped conditions is adapted for subsurface drip irrigation (SDI). This new approach involves one additional variable, the fraction of the irrigation depth contributing to evaporation (fI,Es), which was defined and integrated into the FAO-56 equations for estimating daily water balance from the evaporation layer (0–15cm). Impacts of soil texture, heterogeneity, irrigation depth, design parameters of the irrigation system on fI,Es, and the fraction of the soil surface wetted by irrigation (fw) (and consequently the exposed and wetted fraction (few)), were evaluated through HYDRUS-2D simulations. The modified procedure was compared with the existing FAO-56 method for estimating components of annual ET for wine grape under SDI.The model simulations showed that the fI,Es fraction in a homogeneous, isotropic light-textured soil was minimal (0.04) when SDI was placed at a depth of 25cm. However, in medium and heavy textured soils fI,Es was 4 times larger than in light-textured soils. The value of fw was slightly higher in fine-textured (0.09) than in medium-textured soils (0.07). In Duplex soils with two contrasting textural layers, fw (0.12–0.16) was higher due to the presence of a heavy-textured soil layer just below the drip line. Similarly, in Triplex soils (3 different textural layers), placing the drip line in the middle layer effectively reduced both fI,Es and fw close to zero. In contrast, fw (0.18–0.30) and fI,Es (0.28–0.42) both increased considerably in heterogeneous soils. Both fractions (fw and fI,Es) increased with an increase in irrigation depths, except for fI,Es in loamy sand. The fractions were slightly lower when a drip line was placed at a depth of 10cm (an evaporation zone) than when it was placed on the soil surface. Applying the same amount of water with different discharge rates had little impact on fI,Es and fw fractions. An increase in the drip line spacing proportionally decreased the wetted fraction on the soil surface. Annual evaporation for SDI irrigated wine grapes at the field study site, estimated using the existing FAO-56 procedure, was overestimated by about 5–6% compared to using the modified procedure. However, this deviation between the two approaches increased (18%) for heavier soil textures. It is concluded that the existing FAO-56 procedure needs to be adjusted when used to estimate evaporation under subsurface drip irrigation. However, the impact of the proposed modification on evaporation needs further evaluation under other crops, soils, and climatic conditions.

Fate of Potential Contaminants Due to Disposal of Olive Mill Wastewaters in Unprotected Evaporation Ponds.

The disposal of olive mill wastewaters (OMW) in shallow and unprotected evaporation ponds is a common, low-cost management practice, followed in Mediterranean countries. So far, the fate of potential soil pollutants in areas located near evaporation ponds is not adequately documented. This study investigates the extent in which the long-term disposal of OMW in evaporation ponds can affect the soil properties of the area located outside the evaporation pond and assesses the fate of the pollution loads of OMW. Four soil profiles situated outside and around the down slope side of the disposal area were excavated. The results showed considerable changes in concentration of soil phenols at the down-site soil profiles, due to the subsurface transport of the OMW. In addition, excessive concentrations of NH4+, PO43- and phenols were recorded in liquid samples taken from inside at the bottom of the soil profiles. It is concluded that unprotected evaporation ponds located in light texture soils pose a serious threat to favour soil and water pollution.

Changes in light-textured soil parameters following two successive annual amendments with urban sewage sludge

The generation of considerable amounts of sewage sludge during wastewater treatment is inevitable and should be carefully addressed. Among the various options available for urban sewage sludge management, the agricultural re-use as a fertilizer/soil conditioner has seen a wide acceptance because of the high amount of nutrients and organic matter contained in this biowaste. Accordingly, the aim of this field-scale study was to evaluate the changes in agricultural soil parameters following two successive annual amendments with increasing amounts of urban sludge (0, 40, 80 and 120tha−1year−1). Sludge addition improved the fertility of the topsoil, showing a significant dose-dependent increase of TOC, N, P, and K contents up to the excessive amount of 120tha−1year−1 (1.6%, 0.09, 233 and 21mgkg−1, respectively). Consequently, soil biological parameters such as microbial communities and enzymatic activities (dehydrogenase, phosphatase, protease and cellulase) were all enhanced as well. On the other hand, we noticed also a similar increasing trend of soil salinity (EC and Na+) and phytotoxic heavy metals namely, Cd and Cr (2.4 and 3.8mgkg−1 at 120tha−1year−1). This variation was nonetheless below thresholds; and metal bioavailability to microorganisms and lettuce seeds was likely to be hindered by the non change in soil pH, which varied within a neutral range for all treatments (7.43–7.87). According to the C/N ratio, which reflects organic matter evolution in soil, plots treated at 80tha−1year−1 resulted in C/N values below 15. Therefore, this excessive sludge dose for agricultural reuse is likely to be the best practice that ensures an adequate organic matter mineralization with less contamination after two successive annual amendments.

Effect of nitrogen scheduling on nitrogen use efficiency and performance of wheat (Triticum aestivum L.) in light textured soil

A field experiment was conducted on wheat (Triticum aestivum L.) during Rabi season of 2005-06 at Crop Research Center of Sardar Vallabhbhai Patel University of Agriculture and Technology, Modipuram, Meerut. The experiment was aimed to evaluate the effect of different nitrogen scheduling and LCC based nitrogen scheduling in wheat. The experiment comprised of ten treatments was laid out in Randomized Block Design, with three replications. The major treatments were, control (where no nitrogen was applied ), 50 % N in basal+25 % N at CRI + 25 % at tillering stage, 25 % N in basal + 25 % N at CRI + 25 % N at tillering + 25 % N at jointing stage, 37.5 % N in basal + 25 % at CRI + 37.5 % N at tillering stage, 50 % N at CRI + 50 % N at tillering stage, 50 % N at CRI + 25 % N at tillering + 25 % N at jointing stage, 50 N in basal + 25% N at tillering + 25% N at jointing stage, 25% N in basal + 37.5% N at CRI + 37.5 % N at tillering, 25% N in basal + 50% N at CRI + 25% N at tillering stage, and nitrogen applied on LCC (Leaf colour chart) based. In different nitrogen scheduling treatments, LCC based nitrogen scheduling treatment was found most efficient than recommended and other nitrogen scheduling treatments in terms of increased wheat yield and nitrogen use efficiency. Application of 25% N in basal + 50% N at CRI + 25% N at tillering stage was also found superior than other treatments, increased these parameters, but it was inferior to the LCC based nitrogen scheduling treatment. AE N and RE N also improved due to LCC based nitrogen application. LCC based nitrogen scheduling practice also reduces the over application of nitrogen which can be susceptible to different losses including leaching, ammonium volatilization and runoff.

Long term effect of conservation agriculture in maize rotations on total organic carbon, physical and biological properties of a sandy loam soil in north-western Indo-Gangetic Plains

Maize-based crop rotations are advocated as alternate to rice-based systems in South Asia due to better suitability for diverse ecologies, higher yields with less water use and more palatable maize fodder compared to rice, and increased demand of maize from piggery and poultry industries. Alternate tillage and crop establishment practices are important management strategies for tackling the issues of soil health deterioration and over exploitation of underground water resources, particularly in rice based intensive crop rotations. The conservation agriculture (CA) based tillage and crop establishment practices such as zero tillage (ZT) and permanent raised beds (PB) hold potential to enhance soil organic carbon (SOC), physical and biological properties for sustainability of soil health. Therefore, a long term study was conducted to evaluate the twelve combinations of tillage practices (03) and irrigated intensive maize based crop rotations (04) on organic carbon, physical properties and microbial biomass and enzymatic activities of a sandy loam (Typic Haplustept) soil in north-western India. The tillage practices consisted of ZT, PB and conventional tillage (CT) in main plots and four diversified intensive maize based crop rotations (MWMb: Maize-Wheat-Mungbean, MCS: Maize-Chickpea-Sesbaina, MMuMb: Maize-Mustard-Mungbean, MMS: Maize-Maize-Sesbania) in sub plots. In this study we analysed the SOC, physical and biological properties of soil at various depths after 7 years of continuous ZT, PB and CT in diversified maize rotations. Compared to CT plots, the soil physical properties like water stable aggregates (WSA)>250μm were 16.1-32.5% higher, and bulk density (BD) and penetration resistance (PR) showed significant (P<0.05) decline (11.0–14.3 and 11.2–12.0%) in ZT and PB plots at 0–15 and 15–30cm soil layers. The soil organic carbon (SOC) increased by 34.6-35.3% at 0–15cm, and 23.6-26.5% at 15–30cm soil depths with conservation agriculture (ZT and PB) based crop establishment techniques over CT. Similarly, the soil microbial biomass carbon (MBC) under CA based systems increased by 45–48.9% in 0–30cm profile depth of a sandy loam (Typic Haplustept) soil. Significant (P<0.05) improvement in soil enzymatic activities i.e., Fluorescein diacetate, dehydrogenase, β Glucosidase and Alkaline phosphatase was also recorded in the CA based treatments. Significant (P<0.05) synergistic effects of summer legumes (mungbean and Sesbania) with winter legume/cereal in crop rotations were observed on SOC,WSA, BD, PR and Ksat at 0–15 and 15–30cm depths. Interaction between tillage and crop rotations were significant (P<0.05) for soil organic carbon, physical properties and enzymatic activities. Thus our long-term study suggests that CA based crop management with selected diversified maize based rotations (MCS and MWMb) can be advocated as sustainable intensification strategy in light textured soils of north-western India and other similar agro-ecologies of South Asia.

The Size of P Pools in Soils is Affected by Soil Properties and Compost Addition

ABSTRACTIt is well known that compost amendment can improve soil phosphorus (P) availability, but there are few studies comparing the effect of one compost type on soil P pools of soils which differ in properties. The aim of this glasshouse experiment was to determine the effect of compost (derived from garden waste) application on P pools in soils with different properties planted with wheat. Four soils from two sites were used, with a heavier and a lighter textured soil from each site. The compost was applied as a 2.5 cm thick layer on the soil surface and wheat plants were grown for 63 days. The treatments also included soil without compost and plants. All pots were regularly watered. The soils were sampled on day 0 in the unamended soils and on day 63 in soil without compost and with compost, and plants after removal of the compost layer. Without and with compost the concentrations of most P pools were higher in the two heavier textured soils (16% and 35% clay) than in the two lighter textured soils (8% and 13% clay). Principal component analysis (PCA) showed that the concentrations of most P pools were positively correlated with organic matter, clay, and silt content of the soils. Only the concentration of water-soluble P was positively correlated with sand content. Compost addition increased the concentration of microbial P, sodium bicarbonate (NaHCO3)-Pi, sodium hydroxide (NaOH)-Pi, hydrochloric acid (HCl)-P, and residual P in all soils, whereas the concentration of NaHCO3-Po was reduced and the concentration of NaOH-Po little affected by compost addition indicating that P was transferred from the compost layer with watering. Compared with the unamended soil on day 0, the concentrations of microbial P, NaHCO3-Pi, NaOH-Pi, HCl-P, and residual P on day 63 were higher, whereas the concentrations of the two organic pools (NaHCO3-Po and NaOH-Po) were lower. This suggests mineralization of organic P pools and formation of inorganic P as well as microbial P uptake. These changes occurred in the unamended and compost-amended soils with greater increases over time in the compost-amended soils. It can be concluded that the size of the P pools is predominately affected by soil texture. Compost amendment increases P availability and microbial P uptake but also leads to the formation of less labile P pools such as HCl-P and residual P which could serve as plant P sources in the long term.

Effect of potassium fertilization on leaf physiology, fiber yield and quality in cotton (Gossypium hirsutum L.) under irrigated Mediterranean conditions

The aim of this work was to study the physiological, yield and quality responses of two upland cotton cultivars (Greek and Australian), grown on light-textured soil under irrigated, Mediterranean conditions, to three potassium levels (0, 80, 160kgK2Oha−1). Despite its pivotal role in plant physiology and growth, K supplementation is often neglected by growers due to high cost and complexity with identifying optimal K levels. A rate of 80kgK2Oha−1 was adequate to increase both seedcotton and lint yield and improve fiber length. This was despite the absence of any response of leaf cation concentrations (K, Na, Ca, Mg, their sum and ratios) to K fertilization. On a contrary, K application affected leaf gas exchange physiology by increasing CO2 assimilation rate and stomatal conductance thus leading to reduced leaf temperature and higher leaf water potential and carbon isotope discrimination (Δ). Cultivars did not differ in the leaf gas exchange characteristics and yield but the Australian (Carmen) had markedly better fiber quality, was water conservative and sustained higher leaf K concentrations compared to Greek (Elina). Growth stage (first open flower, full bloom, first open bolls) impacted significantly leaf gas exchange physiology and cation concentrations resulting in reductions of CO2 assimilation rate, stomatal conductance, leaf water potential, specific leaf area (SLA) and N and K concentrations through the growing season. Regardless the growth stage, the lint yield was negatively correlated with Δ, Na and Na/Mg ratio highlighting the importance of the conservative use of water on cotton yield and the detrimental role of Na despite the theoretical cotton’s tolerance. Fiber length was closely correlated to leaf K at the first open boll stage indicating a putative deficiency of K which possibly accelerates cotton maturity. Overall, results of the present work emphasize the essentiality of adequate K supply for cotton physiology, growth, yield and quality, highlight the interactions of K with other nutrients and stress the cultivar selection as a means to encounter soil K inadequacy.

Identification of suitable soils for cultivation of pomegranate (Punica granatum) cv Ganesh

An experiment was conducted during 2008-13 to study the performance of pomegranate (Punica granatum L) cv. Ganesh with respect to changes in soil properties, plant growth, fruit yield and disease incidence on the plants grown under different soil types. After five years of experimentation, soil pH and organic carbon was increased while calcium carbonate content decrease in most of the soils. Plants grown on heavy textured soil have better macro-nutrient uptake, leaf chlorophyll content and vigorous plant growth compared to light textured soil. Fruit yield was highest in the plants grown on clayey soils having 30 cm depth. Plant growth and fruit yield were drastically reduced with the increase in depth of clayey soil (90 and 120 cm). Better quality fruits were produced on the plants grown in gravelly, sandy loam texture soil having depth of 60 cm and even in the plants grown on weathered rock only. Incidence and severity of bacterial blight and wilt disease was higher in the plants grown on clay textured soils compared to light textured soils.

Soil and leaf nutritional constraints in major pomegranate growing states of India

Pomegranate orchards grown under hot, semi-arid to arid tropical climate were surveyed to diagnose nutrient constraints through soil and leaf analysis. A total 347 pomegranate orchards covering an area about 60,000 ha were surveyed in major pomegranate growing areas of Maharashtra, Karnataka and Andhra Pradesh states during 2007 to 2013. Physico-chemical analysis of the soil samples revealed that most of the pomegranate cultivation is on shallow and light textured soils having pH (&lt; 8.9), EC (&lt; 1.86dS/m) and CaCO&lt;sub&gt;3&lt;/sub&gt; (&lt; 10% in majority orchards) which is within tolerable limit for pomegranate cultivation. Soil as well as leaf nutrient status indicated that P was the most limiting nutrient, followed by N while K and Ca was in sufficient quantity. Micronutrient constraints through foliar analysis revealed that Fe content was in sufficiency range in almost all the orchards despite its low availability in the soils. Similarly, leaf Cu content was very low in majority orchards despite its availability in the soil in excess range. Zinc content in the leaves was in sufficient quantity in all the orchards located in all the states. The nutrients should be applied in a balance ratio ensuring periodical application of organics to maintain soil health.

Relationship of inorganic potassium fractions to yield of cauliflower(Brassica oleracea var. Botrytis) and soil properties oflight textured soils of Rangareddy district

Exploring the relationship among inorganic potassium fractions, yield and soil properties were important to know the best extractant for available K for cauliflower in the light textured soils of Rangareddy district. Surface soils in bulk were collected from thirty locations of Rangareddy district and pot culture experiment was carried out. Inorganic K fractions were analysed to evaluate the relative efficiency of extractants in determining the available K. Here, we have investigated the relationships among the soil properties, between soil properties and K uptake, between soil properties and yield, between K fractions and K uptake, between K fractions and yield. Organic carbon (r = 0.65**), available nitrogen (r = 0.60**) exhibited a significant positive correlation with NH4OAc (1N) extractable K. Available potassium extracted by NH4OAc showed a significant positive correlation with NaBPh4 (0.2 M) extractable K (r = 0.93**), 1M HNO3 (r = 0.55**) and also with citric acid extractable K (r = 0.67**). Among all the extractants 1N NH4OAc extractable K showed higher positive correlation with curd yield (r = 0.975**). It had a significant positive correlation with NaBPh4 (0.2 M) extractable K (r = 0.926**).