Alternative tillage and crop residue management in wheat after rice in sandy loam soils of Indo-Gangetic plains

A 3-year field study was conducted to evaluate the effect of three tillage practices (conventional, zero and reduced/strip) with two nitrogen levels (120 and 150 kg N ha⁻¹) applied in primary strips and three crop residue management practices (removal, burning and incorporation) in secondary strips in wheat after rice. Reduced tillage resulted in significantly higher overall mean wheat yield (5.10 Mg ha⁻¹) compared to conventional (4.60 Mg ha⁻¹) and zero tillage (4.75 Mg ha⁻¹). Residue incorporation resulted in highest mean yield (5.86 Mg ha⁻¹) during third year. Maximum mean yield (6.1 Mg ha⁻¹) was obtained in reduced tillage followed by conventional tillage (5.8 Mg ha⁻¹) under residue incorporation in third year. The weed dry weight recorded at 30 days after sowing was highest (0.3 Mg ha⁻¹) under zero tillage and lowest under conventional tillage (0.16 Mg ha⁻¹). Among crop residue management practices, the highest dry weight of weeds (0.22 Mg ha⁻¹) was recorded under residue incorporation. The highest infiltration rate (1.50 cm h⁻¹) was recorded in residue incorporation followed by residue burning (1.44 cm h⁻¹) whereas; the lowest (0.75 cm h⁻¹) in zero tillage. Soil bulk density was the highest (1.69 Mg m⁻³) under zero tillage and the lowest in residue incorporation (1.59 Mg m⁻³). There were no changes in soil available P and K after each crop sequence in relation to tillage practices during first 2 years. Higher organic carbon (5.1–5.4 g kg⁻¹) was measured under zero tillage compared to other treatments. Residue incorporation increased soil organic carbon and available P while higher available K was monitored in burning treatment during the third year. These results suggest that reduced tillage and in situ incorporation of crop residues at 5 Mg ha⁻¹ along with 150 kg N ha⁻¹ were optimum to achieve higher yield of wheat after rice in sandy loam soils of Indo-Gangetic plains of India.     

Phosphorus skipping effect on productivity,profitability and sustainability of rice-wheat cropping systems in Indo-Gangetic plains of India

A field experiment was conducted for eight years at ICAR-Indian Institute of Wheat and Barley Research, Karnal, Haryana, India to study the skipping effect of P application on productivity, profitability and sustainability of rice-wheat cropping system. Rice yield and biomass were 8.35% and 6.6% higher where cowpea was grown after wheat compared to rice-vegetable pea-wheat crop sequence, respectively. Phosphorus application to rice or wheat or both crops exhibited at par rice grain yield, biomass, harvest index. Phosphorus application to both crops or only in rice crop produced maximum and significantly higher wheat yield (4.62 t ha^?1) as compared to P application only to wheat (4.48 t ha^?1). Eight years growing of green gram, cowpea and vegetable pea increased the organic carbon content 42.89, 16.38 and 4.57 %, respectively compared to the initial level. Skipping of P to either crop, by considering 13.5 million ha rice-wheat area, will save approximately Rs 40,500 million (Rs = Indian rupee) or US $ 623 million ($ = Rs 65) per year. Air pollution may be checked, due to saving on diesel in transportation of P fertilizer, to the tune of 60,383 tonnes of CO₂ per year by reducing emission of one of important global warming gas.     

Indicators of soil quality and crop productivity assessment at a long-term experiment site in the lower Indo-Gangetic plains

Deterioration of soil quality under resource-intensive modern agriculture in the face of global climate change poses a huge risk to food security. Because of the complex nature, estimators of soil quality often rely upon a limited set of soil attributes, along with statistical data reduction techniques, for developing quality indices, whilst overlooking biological aspects and regional climatic variability. This study screened the most suitable soil quality indexing approaches for a rice-oilseed-based cropping system in the lower Indo-Gangetic plains (IGP). For this, surface soil samples (0–15 cm) were collected from an ongoing long-term fertilizer experiment with a rice-mustard-sesame cropping system in the IGP. The following treatments were assessed for their effect on soil quality: T₁-control, T₂-NPK (recommended NPK doses), T₃-NPKG (NPK + in situ green manuring), T₄-NPKGB (NPK + in situ green manuring + biofertilizer) and T₅-NPKF (NPK + farm yard manure FYM). We found that total organic carbon (TOC), β-glucosidase, CaCl₂ extractable S, alkaline KMnO₄ oxidizable N, activity of urease, amidase enzyme and mean weight diameter (MWD) were sensitive key indicators of soil quality. The NPKF treatment maintained the highest soil quality status (0.80–0.91), both under productivity and environmental protection goals, owing to the availability of decomposable carbon. Regression analysis showed a better agreement of equivalent rice yield with expert opinion (EO; R² = 0.89) than principal component analysis (PCA; R² = 0.76). Finally, we found that the expert opinion approach with the nonlinear scoring function was the best tool for soil quality assessment of the region.     

Evaluation of alternate menthol mint (Mentha arvensis L.) based intensive cropping systems for Indo-Gangetic plains of north India

The objective of the study was to determine the profitability and employment-generation potential of different cropping systems involving menthol mint (Mentha arvensis L.) as a component of sequential/intercropping in comparison with the most common paddy–wheat–green gram cropping system. Field experiments were conducted at Lucknow, India (26° 5′ N, 80° 5′ E and 120 m above mean sea level) for three years from July 2004 to June 2007. Menthol mint yielded the maximum fresh shoot biomass and essential oil (21.0 t and 151 kg ha^?1, respectively) grown after sweet basil (Ocimum basillicum)–potato followed by paddy–potato–menthol mint (18.9 t and 136 kg ha^?1, respectively) and maize–mustard–menthol mint (17.7 t and 131 kg ha^?1, respectively). Net returns of all the menthol-mint-based cropping systems were 82.6–354% higher than traditional paddy–wheat–green gram cropping system. Maize–garlic–menthol mint + okra was found to be most profitable (77,200 Rs ha^?1) followed by pigeon pea + sweet basil–menthol mint + okra (76,120 Rs ha^?1). Employment-generation efficiency was much higher in cropping systems involving menthol mint and vegetable crops, the highest (2.21 man days ha^?1 day^?1) being in a maize–cauliflower–onion–menthol mint + okra cropping system.     

Planting methods and nitrogen effects on crop yield and soil quality under direct seeded rice in the Indo-Gangetic plains of eastern India

A field trial was conducted during the kharif (rainy) seasons of 2002 and 2003 at the Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India. The trial was carried out to study the effect of planting methods, sources and levels of nitrogen on soil properties, yield and NPK uptake by rice (Oryza sativa L.) under direct seeded condition. Planting methods significantly influenced the physical, chemical and biological properties of soil. Bulk density (1.385 g cm⁻³), organic carbon (0.43%) and soil moisture content (15.46%) were higher in zero till seeding plots than rotavator and conventional seeding. However, infiltration rate, soil temperature, pH and electrical conductivity showed a declining trend under this treatment and were found maximum (11.54 mm h⁻¹, 36.21 °C at 55 DAS, 30.65 °C at harvest, 7.59 and 0.47 ds m⁻¹) with conventional seeding. The maximum population of bacteria (25.60 × 10⁵), fungi (14.26 × 10⁴) and azotobactor (10.19 × 10³) were found in the plot with zero till seeding while in case of actinomycetes the highest population (25.61 × 10⁵) was found in conventional seeding. Nitrogen sources as well as levels failed to bring about any significant change in the soil properties. The highest grain (3825 kg ha⁻¹) and straw yields (5446 kg ha⁻¹) and N, P, K uptake were recorded in conventional seeding and were found significantly superior to zero till seeding (3144 kg ha⁻¹) but it remained at par with rotavator seeding (3585 kg ha⁻¹). Among the nitrogen sources, neem (Azadirachta indica) coated urea produced significantly higher grain (3761 kg ha⁻¹) and straw yields (5396 kg ha⁻¹) with greater NPK uptake than prilled urea and prilled urea + spent mentha. (The distillation waste of mint (Mentha arvensis) herbage is known as spent mentha.) Application of 150 kg N ha⁻¹ produced maximum grain (3828 kg ha⁻¹) and straw yields (5460 kg ha⁻¹) although it remained at par with 100 kg N ha⁻¹ (3738 and 5393 kg ha⁻¹).     

Rehabilitation of alkaline wasteland on the gangetic alluvial plains of Uttar Pradesh,India, through afforestation

A few species of fuelwood trees were established on highly alkaline wasteland at Aligarh (27°5′ N., 78°4′ E.) in a tropical environment. Of these Prosopis juliflora produced maximum biomass (12.05 t ha⁻¹) and had an energy content of 242.11 GJ ha⁻¹ after 3.5 years growth period. The survival percentage of Terminalia arjuna was highest of those the species tried, but their growth and biomass production were inferior to that of Prosopis juliflora and Acacia nilotica. Some of the fuelwood tree plantations were raised without adding any soil amendment but suffered heavy mortality and could not produce any significant quantity of biomass. In another experiment Leucaena leucocephala was identified as a most promising species for afforestation on substandard soils; also it was found that a relatively high population density (of about 7,500 plants per hectare) is required to rehabilitate such land. Of the soil amendments tried, gypsum with farmyard manure and sand in equal proportion gave the better response (gypsum alone was also tried). Two species of shrubs: Sesbania sesban and Tamarix dioca have shown good adaptability in difficult habitats. After five years of afforestation the soil properties of the sites improved significantly, showing marked reduction in pH, EC and ESP values and an increase in organic carbon content.     

Diversity among melon (Cucumis melo L.) landraces from the Indo-Gangetic plains of India and their genetic relationship with USA melon cultivars

We report here the first broad genetic characterization of farmer-developed landraces of melon (Cucumis melo L.) from the Indo-Gangetic plains of India, an area overlooked in previous melon genetic diversity analyses of Indian melon germplasm. Eighty-eight landraces from three melon Groups in two subspecies (C. melo subsp. agrestis Momordica Group, and C. melo subsp. melo Cantalupensis Group and Reticulatus Group) were collected from the four agro-ecological regions (six sub-regions) of two northern states of the Indo-Gangetic plains of India, Uttar Pradesh and Uttarakhand. Significant differences were found among the landraces and eight USA Reticulatus Group reference cultivars for 18 plant and fruit traits: no. of primary branches per plant, days to marketable maturity, sex expression, fruit shape, flesh colour, netting, no. of fruit per plant, fruit weight, shelf life, total soluble solids (°Bx), ascorbic acid (mg/100 g), titratable acidity (%), fruit length and diameter, seed cavity length and diameter, flesh thickness, and resistance to Cucumber mosaic virus. The three melon groups differed significantly for 10 of the plant and fruit traits. Cantalupensis Group and Reticulatus Group accessions were andromonoecious, and the Momordica Group was monoecious. Neighbour-joining (NJ) tree and factorial correspondence analysis (FCA) of simple sequence repeat loci also revealed a high level of genetic variability in this germplasm. The 96 melon genotypes clustered into five groups in the NJ tree analysis: the 16 Indian Reticulatus Group accessions and eight USA reference cultivars formed a distinct group; and the 60 Cantalupensis Group accessions clustered in four other groups with the 12 Momordica Group accessions in a distinct subgroup of one of the Cantalupensis groups. The FCA plot largely confirmed the NJ tree with three distinct groups, one for each melon group. The close affinity of the Indian and USA Reticulatus melons was not unexpected, but it is not clear whether it was inherent in the group and maintained as Reticulatus melons moved from India through Central Asia and Europe to North America, or the result of recent intercrossing of Indian landraces with the USA-derived cultivars and selection for a broad range of Reticulatus type melons.     

Electrical parameters of soils and pedogenesis

A concept of the relationship between the electrical parameters of soils (the electrical resistivity and the natural electrical potential) and their pedogenesis was advanced on the basis of the known classical laws of electromagnetism and the general theory of pedogenesis. It was shown that the electrical parameters of soils primarily depend on the density of the mobile electric charges, which include cations of the soil exchange complex and ions of the soil solution. Model notions were developed to explain the laws of the changes in the electrical parameters in the main genetic soil types for the catenary and zonal levels of the soil cover organization.     

Phosphorus fractions in argentine soils of different pedogenesis

Abstract

The distribution of phosphorus (P) in different organic and inorganic fractions was examined in five Argentinean soils of different pedogenesis. Soils were sequentially extracted to determine resin‐P, bicarbonate‐P, and hydroxide‐P fractions. Inorganic P (IP) predominated in all soils, specially moderately resistant IP (MRIP) in Entisol, Vertisol, and Ultisol. Both MRIP and labile IP (LIP) were important in Mollisol. Organic P (OP) was at a lower concentration in all soils and moderately resistant OP (MROP) was highest in all soils, except for the Mollisol. In intermediate evolution soils, labile P (LP) was very important, Mollisol had the highest value of LP%, and the lowest was for the Ultisol, demonstrating greater dynamics of P fractions in the Mollisol, soils of high productivity in the Pampean Prairie.     

The fate of phosphorus during pedogenesis

The fate of phosphorus (P) during pedogenesis is considered with particular emphasis on vertical distribution within the profile. Information is based on P fractionation studies involving a range of soil sequences in New Zealand. Forms of P in soil parent materials are discussed in relation to soil P transformations. Soil chronosequences, developed in contrasting environments, provide useful information on the pedogenetic pathways of soil P. Although less well understood, soil toposequences can be used to elucidate the effects of slope and drainage on soil-forming processes which involve P.     

Complex pedogenesis of ferrallitic savanna soils in South Sudan

Complex pedogenesis in ferrallitic savanna soils is demonstrated by means of three typical profiles. The information provided includes relative age relationship of soils on the polycyclic pediment slopes, macro- and micromorphological characteristics, some chemical and complete mineralogical data. The authors compare the operation of basic processes of saprolitization (kaolinization, primary mottling) and pedogenesis (homogenization, local, vertical and lateral redistribution of iron) in forest soils formed on deep saprolite, and savanna soils on generally much shallower saprolite. Complex pedogenesis in the latter results from intermittent erosional impact, changes of climate and the stepwise downward weathering and deepening of the solum. All of these factors cause (homo- or heterogenetic) changes of internal hydrological conditions in the whole or parts of the solum. By means of detailed differentiation of ferruginous precipitates in regard to their crystal form (hematite and goethite) and their successive formation and alteration, the authors attempt to elucidate the history of soil formation.     

Integrated nutrient management (INM) on yield trends and sustainability,nutrient balance and soil fertility in a long-term (30 years) rice-wheat system in the Indo-Gangetic plains of India

We analyzed data from a long-term rice–wheat cropping sequence to evaluate the effects of integrated nutrient management (INM) on yield trends and sustainability, nutrient balance and soil fertility of the system. After 30th cycle, grain yield of both the crops significantly declined under control and highest rice and wheat grain yields were obtained when 50% N supplied through green manure and farm yard manure, respectively. The magnitude of yield slope under INM was found considerably higher than 100% recommended fertilizer (RDF). Sustainable yield index (SYI) for both the crops were found lower in control but considerably higher with the 100% RDF and under INM. The soils under all the treatments suffered an apparent loss of K and N (except where organics replacing 50% N). Correlation study also reveals K is the sole factor for the yield sustainability as apparent K balance was negatively correlated with SYI and yield slope.     

土壤时间序列的构建及其在土壤发生研究中的意义

土壤时间序列在研究土壤演化速率与方向、建立土壤发生演化模型上具有重要的价值,并且能为土壤发生学理论的验证提供宝贵的信息。为了获得可靠的结果,时间序列的构建必须包括剖面内与剖面间母质均一性或母质不连续性的判定以及土壤的绝对或相对年龄的判定这两个重要过程。本文综述了土壤时间序列的类型及其构建方式,详细论述了在时间序列建立过程中母质不连续性的判定方式与土壤定年方法,并阐明了土壤时间序列方法在土壤发生研究中的重要意义,旨在为正确建立土壤时间序列、深刻理解土壤发生中的时间因素提供较为详尽的参考。     

Quantifying processes of pedogenesis using optically stimulated luminescence

New analytical techniques have opened up the possibility of addressing rates of soil processes quantitatively. Here, we present the results of an investigation into the use of single‐grain optically stimulated luminescence (OSL) dating to derive rates of soil mixing in the top 50 cm of soil profiles from two toposequences situated in the Werrikimbe National Park in Australia. Of 500 single grains analysed from each sampled depth increment, less than 25% provided a finite age, with the rest of the grains either non‐responsive or dose‐saturated. This proportion of finite‐age grains tended to decrease with soil depth. Median ages of quartz grains increased down the soil profile, with topsoil ages of up to 500 years and subsoil ages of up to 5000 years. Few ‘younger’ grains were found deeper in the profile and few ‘older’ grains near the soil surface. These trends suggest that pedoturbation is resulting in vertical transport of grains through the profile, but that there is a distribution of transport distances, with a poor probability of large transport distances from surface to subsoil or vice versa compared with a more frequent movement of grains to and from the surface in the uppermost 10–35 cm. The calculation of a single age for each soil horizon was unachievable as each horizon contained a heterogeneous mixture of grains with varying histories of transport to and from the soil surface. Soil mixing was confirmed along both toposequences studied. However, the occurrence of minor mixing rates did not lead to a homogenization of the topsoil and adjacent horizons. We postulated that mixing velocities were mostly related to flora at our study site. Vertical soil mixing rates of 0.5 and 0.2 mm year^?1 were calculated from the distribution of finite single‐grain ages.     

A concept of Gleyization and its role in the pedogenesis

Three simple factors ‐ excessive moistening, anaerobic microflora and organic matter, are indispensable and sufficient conditions for gley formation. This process is always characterised by a non‐silicate iron loss from the soil fine earth or soil plasma. Gley formation takes place under conditions of stagnant or stagnant‐percolative water regimes.

In the second case gley formation induces a drastic acidification of the mineral soil part, lessivage, removal of iron, aluminium, calcium, magnesium, bleaching of the soil fine earth, and it appears the features of soil with eluvial, acid, bleached horizons. Therefore soils with such horizons should be regarded as manifestations of gley formation in conditions stagnant ‐percolative water regime on acid, neutral or leached parent material. Under influence of stagnant water regimes Fe of mineral substrat is removed and unconsiderable eluviation of Ca and Mg takes place. pH of parent material does not change or has the trend to increase. In this case does not arise a soil with bleached horizons.     

Anthropic pedogenesis of purple rock fragments in Sichuan Basin,China

Considerable amounts of rock fragments are found in many “Purple soils” developed from purple rocks in the Sichuan basin of southwestern China. We describe the effects of anthropic pedogenetic processes on purple rock fragments associated with soil amelioration by determining changes in rock fragment size distribution, transformation of P and K of purple rocks into soils, and the complexing of purple rock particles (soil mineral particles) with organic matter during anthropic pedogenesis of “Purple soils” in Sichuan basin of southwestern China. The pedogenetic capacity of rock fragments can be expressed by the content of < 2.0 mm particles as weathered products of rock fragment disintegration. The pedogenetic capacity of the purple rocks studied ranges from 0.3% to 6.2% under natural conditions. The rates of P and K transformed from purple rocks are closely associated with the pedogenetic capacity of rock fragments(r = 0.891^??; 0.961^??, n = 16). Digging (simulated by sieving) and crop planting facilitate pedogenesis of purple rock fragments and their mineral nutrient transformations. The soil mineral particles preserve 18%–36% of the organic carbon added as corn straw. The organic carbon is complexed after corn straw is mixed with < 1.0 mm soil mineral particles for 1 year. The improvement of newly reclaimed purple soils is enhanced by the complexing effect of organic substances with purple rock particles. The pedogenesis of purple rock in Sichaun basin can be accelerated by anthropic activity, such as tillage, crop planting, fertilization, and land reclamation.     

石灰石成土过程中Zn在土壤中的演化和重新分布

The long-term redistribution of Zn in a naturally Zn-enriched soil during pedogenesis was quantified based on mass balance calculations. According to their fate, parent limestones comprised three Zn pools: bound to calcite and pyritesphalerite grains, bound to phyllosilicates and bound to goethite in the inherited phosphate nodules. Four pedological processes, i.e., carbonate dissolution, two stages of redox processes and eluviation, redistributed Zn during pedogenesis. The carbonate dissolution of limestones released Zn bound to calcite into soil solution. Due to residual enrichment, Zn concentrations in the soil are higher than those in parent limestones. Birnessite, ferrihydrite and goethite dispersed in soil horizon trapped high quantities of Zn during their formation. Afterwards, primary redox conditions induced the release of Zn and Fe into soil solution, and the subsequent individualization of Fe and Mn into Zn-rich concretions. Both processes and subsequent aging of the concretions formed induced significant exportation of Zn through the bottom water table. Secondary redox conditions promoted the weathering of Fe and Mn oxides in cements and concretions. This process caused other losses of Zn through lateral exportation in an upper water table. Concomitantly, eluviation occurred at the top of the solum. The lateral exportation of eluviated minerals through the upper water table limited illuviation. Eluviation was also responsible for Zn loss, but this Zn bound to phyllosilicates was not bioavailable.     

Morphological diagnostics of pedogenesis on the anthropogenically transformed floodplains in Moscow

At present, many parts of river valleys, including floodplains, are being actively used for urban construction. This leads to the disturbance of normal functioning of the valleys; alluvial deposits and soils become buried under the thickness of various anthropogenic materials. Four profiles of typical urban soils (urbanozems) developed on the floodplain of the Moskva River and its small tributaries have been studied. The macro- and micromorphological characteristics (including data of submicroscopic studies) and the chemical and physicochemical properties of these soils are analyzed. It is shown that the influence of ground-water on the anthropogenically transformed soils of floodplains and low terraces is preserved even upon the cessation of regular flooding. The substitution of urban pedosedimentogenesis for alluvial pedosedimentogenesis has a gradual character with a transitional stage of simultaneous occurrence of both processes. Clayey and clayey-calcareous infillings in the middle-profile horizons and newly formed phosphates of iron and calcium in the lower horizons affected by the groundwater can be considered typical diagnostic features of the urban-alluvial pedogenesis.