Sodic Soils Research Articles

Soil degradation assessment of some selected land use in two Agro ecological zones of Gombe State, Nigeria

Soil degradation remains a global environmental phenomenon caused by anthropogenic activities. The assessment of degradation status of soils in some selected land uses of two agro ecological zones of Gombe state was carried out. Representative soil samples from four land uses were collected from 0 - 30 cm depths (cultivated, Fadama, forest and mining land). The soil samples were labeled, air-dried, crushed, sieved through a 2 mm mesh, and subjected to various physical and chemical analyses. Data collected were subjected to descriptive statistics and soil degradation assessment was done following standard procedures. The levels of degradation of soils were assessed using the standard indicators and criteria for land degradation assessment by the Global Assessment of Land Degradation. Analytical data from each sample were placed in a degradation class by matching the soil characteristics with the land degradation indicators, while estimation of the overall degree of degradation was arrived at mathematically, using physical, chemical, and biological parameters. The results shows that the textural class of the soil ranged from clay to sandy loam. Permeability ranged from 0.10 to 7.97 cm hr-1 corresponding low to high permeability. Bulk density ranged from 1.24 to 1.62 g cm-3. Organic matter was very low in all the study sites. Available phosphorus ranged from 6.2 to 15.5 mgkg-1. Total nitrogen was predominantly low (0.05 – 0.08%) in all the land uses. Exchangeable Sodium Percentage (ESP) of the sites depicted that most of the soils were non sodic soils (0.71 – 1.61%). The potential for all the land uses are moderately degraded varied from Fadama land (41.67%), cultivated land (44.44%), mining land (47.22%) and forest land (50%), respectively. The major barriers in the study areas were low fertility, and soil conservation measures. In order to optimize crop production in these areas, there may be need to introduce soil conservation measures. The practice may include use of farm yard manure, compost, crop residues, green manure or poultry manure to boost soil fertility. Regular monitoring of the fertility status of the soils is encouraged.

Effect of Sodic Soil and Water Logged Condition on Forage Crop and Their Application in Breeding

Soil salinity is a growing issue in many parts of U.P. The use of improved salt-tolerant forage grasses assists farmers in increasing production and reclaiming saline soil. Salinity stress reduces crop yield by affecting plant growth and limiting land use. Forage Crops are intrinsically bio diverse. The monitoring, evaluation and research on Forage cultivation must be tailored to this special Sodic Soil farming system. Forage are beneficial for water saving and sometimes it is drought tolerant crops. Therefore they must be viewed as climate change compliant crops. Forages have never been given importance in agriculture by farmers as the area devoted to fodder crops is either neglected or almost constant since many decades and it is about 3% of the total cropped area in the state. About 0.94 m ha area is under forage production and there is no scope of its further expansion because of small land holdings and existing pressure for food and cash crops on agricultural land. However, possibility exists for improvement of productivity through appropriate management practices suited to different ecosystems. Due to industrialisation and habitat use, agricultural land is becoming increasingly scarce as the global population is growing at an alarming rate. In order to meet the need for food, it is necessary to use land that has been impacted by salt. Although traditional breeding has had considerable success, its use is restricted because of obstacles to reproduction and a lack of genetic diversity among the main crops. However, more work is needed to ensure the successful release of salt-tolerant cultivars in the field.

Screening of Rice Genotypes against Sodicity in Relation to Physiological and Biological Traits

The study aimed to screen the rice genotypes against sodicity in relation to physiological and biological traits to identify the tolerant and susceptible genotypes. The field experiment was carried out at the Research Farm of Dr. Rajendra prasad central agricultural university, Pusa, Samastipur, Bihar during Kharif season of 2019-2020. The experiment was based on randomized block design with 30 plots in each of 3 replications where each replication consists of 30 rice genotypes. A total of 30 rice genotypes were screened of which 25 are exotic and 5 are indigenous. The exotic genotypes are GPV 1, GPV 2, GPV 3, RMS 1, RMS 2, RMS 3, RMS 4, RMS 5, RMS 6, RMS 7, RMS 8, SRL 1, SRL 2, SRL 3, CNN 1, CNN 2, KRH 4, PVP 221, MTU 1010, VR 181, PS 344, MTP 1, Vardhan, Rasi, CSR 23 (Check) while Prabhat, R. Sweta, R. Bhagwati, R. Mahsuri and Rajshree are the indigenous ones. The physiological and biological traits were evaluated at tillering and pre-flowering stages and their inter-relationship among various physiological parameters are established. The genotypes such as SRL 1, GPV 1, GPV 2, GPV 3, and Rajendra Mahsuri show the highest chlorophyll content, SPAD value, peroxidase and catalase activity, proline content, RLWC content, and MSI percentage, and the lowest was found in Prabhat, Rasi, and Rajendra Bhagwati. Based on response with regard to SPAD value, RLWC, and MSI the genotypes such as SRL 1, GPV 1, GPV 2, GPV 3, and Rajendra Mahsuri show positive increase compared to CSR 23 (Check). The inter-relationship concerning to various physiological parameters shows a strong significant and positive correlation among each other at tillering and pre-flowering stages. However, Total chlorophyll at the tillering stage was found to bear a highly significant correlation with all the physiological parameters except relative water content and membrane stability index. The genotypes such as SRL 1, GPV 1, GPV 2, and GPV 3, Rajendra Mahsuri possess better potential in sodic soil than the rest of the genotypes taken in the experiment with regard to various physiological parameters (taken as salt indices) by counteracting or minimizing the sodicity effect of sodium ion. The greater synthesis of antioxidant enzymes like catalase and peroxidase plays an important role in plant adaptation which effectively support to withstand and perform well in sodicity conditions hence SRL 1, GPV 1, GPV 2, GPV 3, and Rajendra Mahsuri categorized as salt tolerant genotypes which have great potential to boost up the rice production in sodic soil condition while Prabhat, Rasi and Rajendra Bhagwati categorized as salt susceptible genotypes. Thus, this study will be helpful for the identification of tolerant and susceptible genotypes through screening and pave way for the development of stable and high-yielding genotypes for the improvement of rice production under sodic soil.

Comprehensive assessment of pollution indices, sources apportionment and ecological risk mapping of heavy metals in agricultural soils of Raebareli District, Uttar Pradesh, India, employing a GIS approach

AbstractIn the environment, heavy metal contamination is a well known problem due to its persistence and toxicity. Heavy metal pollution has significantly affected soil properties and functions, resulting in significantly increased land degradation as a result of anthropogenic interventions that include mining and various industrial and agriculture activities. While heavy metals pollution in soil have been studied very rarely in this District, this paper explores the current status of agricultural soil pollution by heavy metals in Raebareli. This study identifies heavy metals as well as their quantities in the soil and their spatial distribution; our study employed various pollutant indices and geographical information system (GIS) techniques. This research work evaluated the physiochemical properties, the pollution load index (PLI), contamination factor (CF) and the degree of contamination and geoaccumulation (Igeo) in sodic soils of the Raebareli District, Uttar Pradesh, India. Uchahaar site (US) has the most polluted soil, while the Bacharawa site (BS) has the least contaminated soil. The soil quality has degraded due to anthropogenic interventions at most sites. There is slight to moderate contamination by heavy metals at all sites. The Igeo values in subSites US1, US2 and US3 included high levels of Cu, Zn, Pb, Mn and Sr. SubSites BS2 and BS3 have high Sr levels and US1 has a high As level all these Subsites have high anthropogenic influences. The PLI values indicate that most of the study subSites come under a slightly polluted class, except US1 where the PLl was > 3 indicating severe heavy metal pollution at this site. All the pollution indices have then been utilized for building maps using the IDW method of interpolation. The spatial projection of PLI and ecological risk index (Er) values suggest that the northern part of Raebareli has a high pollution load and ecological risk in terms of heavy metal pollution. This study provide valuable information that policymakers could use to develop an appropriate plan to control pollution within the agricultural sector.

Correlation of soil physico chemical properties with a yield of green gram (Vigna radiata L.) by soil amendments and foliar nutrition under sodic soil condition

In India, about 3.77 million ha of the country's geographical area is affected by sodicity. There is an urgent need to minimize further land degradation and restore the fertility of degraded soils to meet the growing demand for food. The most effective way to overcome salt stress is by applying nutrients through soil and foliar. In this context, a field experiment was conducted at Anbil Dharmalingam Agricultural College and Research Institute (ADAC & RI), Tiruchirappalli, in the summer of 2022 to study the reclamation potential of soil amendments and foliar nutrition in sodic soil. The experiment was laid out in a split-plot design with three replications. The treatment comprised of soil amendments viz., M1- Pongamia green leaf manure (GLM) @ 6.25 t ha-1, M2- Pressmud @ 10 t ha-1, M3-CSR GROMOR @ 25 kg ha-1, M4-Gypsum @ 50 % GR, M5-Gypsum @ 50 % gypsum requirement (GR) + Pongamia GLM @ 6.25 t ha-1, M6-Gypsum @ 50 % GR + Pressmud @ 10 t ha-1, M7-Gypsum @ 50 % GR + CSR GROMOR @ 25 kg ha-1 and M8- Farmers practice, in main plots and foliar nutrition viz., S1- Foliar spray (FS) of CSR GROMOR @ 3% @ 30 DAS, S2-FS of Brassinosteroid (BRs) 0.2 ppm @ 30 DAS and S3-FS of Melatonin 60 ppm @ 30 DAS in sub plots. The results showed that gypsum @ 50 % GR + Pressmud @ 10 t ha-1+ FS of Brassinosteroid 0.2 ppm @ 30 DAS(M6S2) registered significantly (P=0.05%) lowest pH (8.07), ESP (11.62%), exchangeable Na+ (2.93 c mol (p+) kg-1) with higher exchangeable Ca2+(11.23 c mol (p+) kg-1), Mg2+ (8.09 c mol (p+) kg-1) and K+(0.82 c mol (p+) kg-1). It also increased soil available nutrients (235.6, 24.57 & 309.6 kg NPK ha-1) and grain yield (1110 kg ha-1) of green gram. However, it was on par with gypsum @ 50 % GR + CSR GROMOR @ 25 kg ha-1 + FS of Brassinosteroid 0.2 ppm @ 30 DAS(M7S2). Hence it was concluded that the application of gypsum along with pressmud or CSR GROMOR combined with FS of brassinostroid had a remarkable effect in reducing soil sodicity and increasing the productivity of green gram.

Effects of irrigation regimes and brown manuring on physiological parameters and yield of direct seeded rice (TRY 3) under sodic soil condition

Direct seeded rice (DSR) production has been recognised as a more efficient way for conserving both labour and water. However, in regards to irrigation and brown manuring (BM), DSR has gotten relatively little attention. Hence, a field study was conducted to findout the effect of irrigation and brown manuring on physiological characters and yield of DSR (TRY 3) under sodic soil condition. The experiment was laid out in a split plot design and each replicated thrice. The main plots consist of irrigation after 10 cm (M1) and 15 cm (M2) depletion of field water tube and irrigation after the disappearance of ponded water (M3). The sub plots consist of sesbania BM at 15 (S1), 20 (S2) and 25 kg ha-1 (S3), PE Pretilachlor at 0.45 kg ha-1 fb PoE Bispyribac sodium at 25 g ha-1 + hand weeding (HW) on 45 DAS (S4), HW (S5) and weedy check (S6). Results revealed that higher SPAD value was recorded under M3 which was on par with M1. Among sub plots maximum SPAD value was recorded with S5 followed by S4 and S2. Treatment M2 recorded maximum proline content. There is no significant difference found in relative water content (RWC). However, higher RWC content was observed in M3. At the same time, higher grain and straw yield were recorded under M3 with S5, followed by M1 with S5. However, due to a large amount of water required and the higher labour costs associated with hand weeding, M1 with S2 was the best choice for increasing DSR productivity.

Rhizobacteria improve rice zinc nutrition in deficient soils

The deficiency of zinc (Zn) in rice grown under partially reclaimed sodic soils is mainly because of the low solubility of Zn minerals. Augmenting the rhizosphere interaction with acclimatized native Zn solubilizing rhizobacteria (ZSB) can be a promising approach to cope with poor Zn nutrition of crops under deficient soils. This study was designed to isolate ZSB from the rhizosphere bacterial community of plants growing in soils of zinc mines and sodic environments and evaluate their performance in Zn nutrition of the rice. Isolates were assessed for in vitro Zn solubilization and identified by the amplified 16S rRNA gene using universal primers. The selected ZSBs were evaluated using a complete randomized block design with three replications for their response to Zn nutrition of rice in soils with high and low DTPA extractable Zn. The ZSB population was greater in rhizospheric soils of yellow sweat clover, rice, sorghum, and maize (6.2–10.3 × 103) than wheat (2.5 × 103). The Zn mine soils harbour a 2.96 times higher ZSB population than sodic soils. The ZSB population showed a strong negative correlation with the pH and EC of the soil (r > −0.90, p < 0.01). Bacillus paramycoides strain-1, B. paramycoides strain-2, B. cereus, and Enterobacter soli, isolated from rhizospheric soil; solubilized 228.4, 146.5, 174.6, and 334.0 μg mL−1 Zn from zinc oxide under in vitro conditions. However, rice plants showed a selective response in forging an association with inoculated ZSB. Only B. paramycoides strain-1 had exhibited a 17% increase in Zn uptake over uninoculated control. Inoculation with B. paramycoides strain-1 also caused a 22–24% increase in the water-soluble plus exchangeable fraction of Zn in deficient soils. This study concludes that using native rhizobacteria can be a practical option for managing Zn deficiency in alkaline soil conditions. The study also highlights the importance of soil native micronutrient levels in the success of the rhizobacteria –phytobionts interaction for crop nutrition.

Revegetating Saline–Sodic Soils With Salt‐Tolerant Grasses

Revegetating Saline–Sodic Soils With Salt‐Tolerant Grasses

Influence of biochar and aluminum sulfate on rice growth and production in saline soil

ABSTRACT Soil salinization is a major threat to crop production. Biochar and aluminum sulfate as soil amendments are critical for improving rice (Oryza sativa L.) productivity under saline-sodic conditions. This study explored the effects of rice-husk biochar and aluminum sulfate on rice growth, biomass, yield, and soil properties under saline-sodic conditions. The experiment was carried out in an experimental field located at the Jilin Agricultural University, China. Five treatments, viz., T0 (no biochar, no aluminum sulfate, no nitrogen), T1 (no biochar, no aluminum sulfate, with NPK), T2 (aluminum sulfate and NPK), T3 (biochar and NPK), and T4 (biochar, aluminum sulfate, and NPK), arranged in a completely randomized design with five biological replicates, were assessed. Compared to T0, plant height, tiller number, leaf dry weight, panicle dry weight, sheath dry weight, stem dry weight, and total dry biomass significantly increased by 14.67%, 56.39%, 60.13%, 59.53%, 39.00%, 58.36%, and 55.99%, respectively, with T1. Compared to T0, the grain yield significantly increased by 82.79% with T1. Additionally, biochar and aluminum sulfate applications significantly decreased the Na+ concentration in different rice organs and considerably increased the K+ concentration and consequently, the K+/Na+ ratio. Moreover, compared to the control, the soil pH, Ca2+, Mg2+, CO32-, and Cl- concentrations under T1, T2, T3, and T4 treatments were substantially improved. Therefore, biochar and aluminum sulfate applications can alleviate saline-sodic stress, improve soil health, and increase rice productivity on saline-sodic soils. The study findings are anticipated to help develop new management strategies for improving rice production under saline-sodic conditions.

Restoring ecological function to saline–sodic soils in South Dakota with perennial grass mixtures

AbstractRevegetation of saline–sodic soils is challenging. Over 10 million saline–sodic hectares are intertwined with highly productive soils in the Northern Great Plains, with 3.4 million ha in South Dakota. Establishing salt‐tolerant perennial plants provides soil cover and remediates barren areas. Two perennial salt‐tolerant grass mixes [Mix 1: slender wheatgrass (Elymus trachycaulus [Link] Gould ex Shinners) + beardless wildrye (Leymus triticoides [Buckley] Pilg.); Mix 2: slender wheatgrass + creeping foxtail (Alopercurus arundinaceus Poir.) + western wheatgrass (Pascopyrum smithii [Rydb.] Á. Löve) + ‘AC Saltlander’ green wheatgrass (Elymus hoffmannii K.B. Jensen &amp; K.H. Asay)] were dormant‐planted in 2018 and 2019 along a soil catena with high [electrical conductivity (EC1:1) = 0.39 dS m–l; 72 mg kg–1 Na+], moderate (EC1:1 = 1.64 dS m–l; 343 mg kg–1 Na+), and low (EC1:1 = 3.87 dS m–l; 1,680 mg kg–1 Na+) productivity zones. Vegetative biomass was measured after seeding (2018, 2019) and during growth (2020, 2021), and compared with areas seeded to maize (Zea mays L.) and a nonplanted area. Biomass varied with year and productivity zone. Except in 2018, grasses had greater biomass in the moderate and low productivity zones than maize. The sodium content of grass biomass in 2020 and 2021 was 10× greater in the low than in the high and moderate productive zones (0.25 vs. 0.02%, respectively) but could be suitable for livestock feed. By 2021, grass biomass was similar for both mixes in all zones, and the grasses spread into nonplanted areas.

Effect of Different Amendments and Inorganic Nutrient Management Approaches in Correcting Sodicity under Paddy Eco System

Agricultural production in sodic soil may be hindered by its unfavorable physicochemical properties. In order to find effective measure to improve the health of sodic soil and make it to favourable for crop production, a field experiment was conducted at ZARS VC Farm Mandya to study the effect of different amendments on properties of sodic soil. The experiment was laid under split plot design with inorganic nutrient management viz., RDF, SSNM and STCR as main treatments and amendments such as press mud, gypsum and Mangala setright, (a commercial soil conditioner containing 15% calcium and 3% magnesium and 5% sulphur) as sub treatments. Results of experiment revealed that application of gypsum significantly reduced pH to 8.5 from 8.96 of initial soil which was on par with application of setright at 600kg/ha (8.68) and press mud (8.69). Whereas exchangeable sodium and ESP was reduced significantly due to application of setright at 400 kg/ha (1.78 cmol/kg and 6.52 respectively) and pressmud at 100% GR (1.85 cmol/kg and 7.03) compared to control (3.69 cmol/kg and 13.72 respectively) and initial soil. Thus application of Mangala Setright at 400kg/ha or pressmud at 100% GR are more beneficial in rectifying sodicity of soil.

Nano-gypsum in low dose improves the physicochemical properties of saline-sodic soil

ABSTRACT Increased Na+ ions negatively affect soil physicochemical characteristics. We ran a pot incubation experiment for 2 months and a leaching experiment for another 2 months to monitor the effects of nano-gypsum (NG, <100 nm) in low affordable doses on improving saline-sodic soil physicochemical characteristics. Treatments included a control (CK), conventional gypsum (CG; ≤ 0.5 mm) at 100% CG requirement (8.9 t ha−1: CGR), and three low doses of NG (240, 480 and 960 kg ha−1 = 2.7%, 5.4% and 10.8% of the CGR). Both applications of NG at 10.8% of CGR and the CG at 100% of CGR followed by leaching had the best effect and performed almost equally. However, the use of 960 kg NG ha−1 had the most pronounced effect, where it decreased the bulk density (16.4%) and increased stable soil structure (46.2%). Also, the soil hydraulic conductivity increased by approximately 2.4 times, which helped increase the Na-removal efficiency by 68.9%. Moreover, it decreased soil reaction, electrical conductivity and exchangeable-Na percentage by 15.9%, 39.7% and 71.4% compared to the CK, respectively. Therefore, the NG may introduce novel and alternative application strategy that allows for lower application rate with an adequate gypsum requirement.

The release of petroleum hydrocarbons from a saline-sodic soil by the new biosurfactant-producing strain of Bacillus sp.

Adsorption of old-aged petroleum hydrocarbons to the soil solid phase, which causes biosurfactant loss of performance, is among the limiting factors for the remediation of the saline-sodic soils contaminated with petroleum. Therefore, to find a functional biosurfactant in oil-contaminated saline-sodic soils, the efficiency of 39 bacteria isolated from petroleum-contaminated soils was evaluated. The strains were cultured in the Bushnell–Haas medium, and the produced biosurfactants and bioemulsifiers in this medium were extracted using chloroform/methanol and ethyl acetate extraction methods, respectively. Their partial purification was performed by column chromatography, and eventually, their performance in releasing TPH from the contaminated soil was evaluated. The soil test results revealed that the highest TPH releases due to the effects of the biosurfactants and bioemulsifier produced from SHA302, SH21, and SH72 isolates were 42.4% ± 0.2, 21.6% ± 0.15 and 24.3% ± 0.91, respectively. Based on the 16S rRNA gene sequence, the SHA302 strain showed 93.98% phylogenetic similarity with Bacillus pumilus strain ATCC 7061. The Fourier transform infrared spectroscopy and thin-layer chromatography results proved that the biosurfactants produced by isolates SHA302, SH21 and SH72 showed lipopeptide, glycolipoprotein and glycoprotein natures, respectively. The performance of the biosurfactant produced by SHA302 isolate indicated that it could be used as a good candidate for releasing TPH from saline-sodic soils with old contamination and facilitating the degradation of hydrocarbons.

Effects of Biochar on the Microenvironment of Saline-Sodic Soil and Maize Growth

Biochar is a valuable soil amendment substance. However, no systematic study has investigated the effects of biochar on the microenvironment of saline-sodic soils and maize yield in cold areas of Heilongjiang Province. We investigated variations in soil physicochemical properties, soil bacterial and fungal community structure, maize root formation, plant dry matter accumulation, grain filling rate, and maize yield in saline soils treated with biochar (0, 20, 40, and 80 t/ha). Biochar improved saline soil properties and structure, slightly decreasing bulk density and pH and increasing the water-stable aggregate stabilization rate. Furthermore, the relative abundances of Sphingomonas, Lysobacter, Nitrospira, and Gemmatimonas and the fungal genus Guehomyces were increased, promoting the conversion of soil organic carbon and available nitrogen and phosphorus. Moreover, biochar reduced the relative abundance of some fungal pathogenic genera, including Fusarium, Gibberella, Cladosporium, Alternaria, and Epicoccum. However, shifts in soil bacterial and fungal community structure were indirectly driven by biochar-induced changes in soil physicochemical properties, with organic carbon as the most critical. Biochar promoted maize growth, development, and yield (root length, surface area, volume, dry matter accumulation, grain filling rate, and final weight). Biochar application at 40 t/ha had the greatest effect on soil microenvironment improvement, with the highest maize yield.

Integrated Application of Trichoderma Mixture and NPK Enhances the rice Productivity in Sodic Soil

Abiotic stresses due to changing environmental conditions and intensive agriculture are causing soil salinity and sodicity leading tosoil deterioration. It directly affects nutrient availability and uptake and reduces plant productivity. The microorganisms are known toimprove the availability of nutrients in the soil and therefore, the present work aimed to maximize the use of applied fertilizers and boostthe productivity. The effects of the Trichoderma mixture (TrichoMix) and NPK on plant growth and rice yield in degraded land underfield conditions was studied. The abiotic stress tolerant Trichoderma strains comprising of T. koningiopsis (NBRI-PR5) and T. asperellum(NBRI-K14) were used in the treatments (i) Control (Cont.), (ii) NPK, as per recommended dose (NPK100%) (iii) Trichoderma mixture (NBRIPR5+NBRI-K14) (TrichoMix) (iv) TrichoMix + NPK50%. Significantly higher plant growth and yield (6.57q/h) was obtained in TrichoMix+NPK50% treatment. The improvement in rice production in the treatment TrichoMix +NPK50% was ascribed to the significant changes insoil physiochemical characteristics such as water holding capacity (35%), bulk density (40%), total organic carbon (42%), available N(39%), P (44%), K (48%) and microbial biomass carbon (88%). The results conclude that the mixture of T. koningiopsis (NBRI-PR5) and T.asperellum (NBRI-K14) may be recommended as sodic soil amendment to increase plant growth and yield in combination with chemicalfertilizers to support rice cultivation.

Effect of Different Sources of Nitrogen Application on Rice Yield and Soil Health in Saline Sodic Soil

Effect of Different Sources of Nitrogen Application on Rice Yield and Soil Health in Saline Sodic Soil

Are Climate-Dependent Impacts of Soil Constraints on Crop Growth Evident in Remote-Sensing Data?

Soil constraints limit plant growth and grain yield in Australia’s grain-cropping regions, with the nature of the impact dependent on climate. In seasons with low in-crop (short for “during the crop growing season”) rainfall, soil constraints can reduce yield by limiting soil water infiltration, storage, and crop water uptake. Conversely, soil constraints can exacerbate waterlogging in seasons with high in-crop rainfall. When average in-crop rainfall is experienced, soil constraints may only have a limited impact on yields. To investigate the relationship between climate and the impact of soil constraints on crop growth, long-term time series yield information is crucial but often not available. Vegetation indices calculated from remote-sensing imagery provide a useful proxy for yield data and offer the advantages of consistent spatial coverage and long history, which are vital for assessing patterns of spatial variation that repeat over many years. This study aimed to use an index of crop growth based on the enhanced vegetation index (EVI) to assess whether and how the within-field spatial variation of crop growth differed between years with different climates (dry, moderate, and wet years, as classified based on in-crop rainfall). Five fields from the grain-growing region of eastern Australia were selected and used to assess the consistency of the spatial variation of the index for years in the same in-crop rainfall category. For four of the five fields, no evidence of patterns of climate-dependent spatial variation was found, while for the other field, there was marginal evidence of spatial variation attributable to wet years. The correlation between measured data on soil sodicity (a soil constraint that might be expected to impact crop growth most in wetter years) and average EVI was investigated for this field. The results showed a stronger negative correlation between average EVI and sodicity in wet years than in dry years, suggesting that sodicity—through its impacts on soil structure and water movement—might be a driver of the spatial variation of crop growth in wet years for this field. Our results suggest that although there may be cases when climate-dependent within-field spatial variation of crop growth is detectable through remote-sensing data (through the multi-year consistency of the within-field variation), we should not expect this to be evident for fields as a matter of course.

Irrigation water quality, gypsum, and city waste compost addition affect P dynamics in saline-sodic soils

The amendments used for sodicity reclamation also profoundly influence P dynamics and leaching losses. This study characterized the effect of irrigation water quality on P dynamics and leaching from saline-sodic soil during reclamation utilizing gypsum alone or in combination with manure and city compost. Changes in properties of unleached and leached soils were fitted with labile P pools using redundancy analysis. The relation between leachate properties and P loss was explained by means of monitoring leachate properties up to ten pore volumes. During incubation, the water-extractable P (PH2O) concentration was greater than Olsen's P (PNaHCO3) in all treatments. The PNaHCO3 decreased in proportion to the amount of gypsum applied. Applying the organics with gypsum increased the PNaHCO3, PH2O, and organic P concentration compared to gypsum alone. The labile P pools in soil were positively correlated with HCO3− content (r = 0.39–0.77; P < 0.05) of leached and unleached soils. Adding gypsum and compost caused a 10–14% decrease in cumulative P leaching. The cumulative P leaching were greater with rainwater compared to saline water of SAR (sodium adsorption ratio) 5 and 15. The CO32−, HCO3−, pH, and SO42–content of the leachate explained about 71% variability in total P leaching (adj. R2 = 0.71; P < 0.001). This study concludes that low electrolyte water had a greater risk of P leaching and associated environmental pollution. Leaching of the saline–sodic soil amended with gypsum and city waste compost with low SAR saline water can reduce P leaching compared to good quality rainwater.

Fractions, stability, and influencing factors of soil organic carbon under different land-use in sodic soils

Salt-affected soils have considerable carbon sequestration potential in aboveground biomass and soil organic carbon (SOC). However, organic carbon pool characteristics and the significant important factors affecting the land use of sodic soils have not been clearly elucidated. In this study, 252 samples were collected from 20 typical sodic soil sites across the western Songnen Plain, China. This study investigated the effects of five land-use types, that is, saline wasteland (SWL), degraded grassland (GL), forestland (FL), upland (UL), and paddy fields (PF), on sodic soil SOC fractions and stabilities to find that UL and PF decreased salinity and alkalinity, but increased soil nutrient and water stability aggregate (WSA) contents and stability. Compared with degraded natural land-use types (SWL and GL), FL and croplands (UL and PF) increased the physical protection of SOC and aggregate-associated SOC contents. Furthermore, cropland, especially PF, increased nonlabile organic carbon (NOC) (7.47 g kg−1), labile organic carbon (LOC) (3.79 g kg−1), dissolved organic carbon (DOC) (0.16 g kg−1), and mineralizable organic carbon (MOC) (0.41 g kg−1) fractions. Furthermore, compared with degraded natural lands, PF increased NOC ratios (59.65%) and carbon management index (CMI) (126.1), thus increasing organic carbon content and stability. Structural equation modelling revealed that improvements in soil properties, total nitrogen (TN), WSA, electrical conductivity (EC), and pH were the crucial factors for increasing SOC stock in sodic soils. We concluded that the positive effect that PF had on SOC content and stability were much greater than that of the other land-use types, and that PF was the optimal management practice for increasing SOC sequestration capacity in sodic soils.

Alternatives to rice-wheat cropping system under partially reclaimed sodic soils

A field experiment was conducted during 2013-14 to 2015-16 at Central Soil Salinity Research Institute, Regional Research Station, Lucknow to find out the alternate to rice (Oryza sativa L.)- wheat (Triticum aestivum L.) cropping system under partially reclaimed sodic soils. Four cropping systems, viz. rice (Oryza sativa L.)- wheat (Triticum aestivum L.), sorghum (Sorghum bicolor)-berseem (Trifolium alexandrinum), sweet basil (tulsi) (Ocimum basilicum L.)-matricaria (Matricaria chamomilla) and chilli (Capsicum spp.)-garlic (Allium sativum) were evaluated in the light of sustainability, potentiality and profitability. Maximum rice equivalent yield (14.21 t/ha) and production efficiency (61.25 kg/ha/day) were recorded with sweet basil-matricaria cropping system whereas, highest land use efficiency (78.35%) was observed under sorghum-berseem fodder based cropping system. Highest water use efficiency (150.72 kg/ha cm) was recorded with chilli-garlic cropping system followed by sweet basil-matricaria, but the total amount of water used was more (125.65 cm) in rice-wheat system. The water requirements of sorghum-berseem, sweet basilmatricaria and chilli -garlic cropping systems were 8.0, 19.8 and 31.8% less than the rice-wheat cropping system. Among the cropping systems evaluated, maximum energy input (27.50 MJ/ ha) and output (314.46 MJ/ha) were analyzed in rice-wheat system. Whereas, maximum energy use efficiency (11.99) was found with sweet basil- matricaria followed by sorghum-berseem (11.91) cropping systems. Highest soil ameliorative potential was established with sweet basil -matricaria cropping system than rest of the cropping systems. Highest net return (₹ 63222/ha) and benefit: cost ratio of 2.74 was deliberated with medicinal and aromatic crop based sweet basil-matricaria cropping system.