Long–term effect of crop rotation and nutrient management on soil–plant nutrient cycling and nutrient budgeting in Indo–Gangetic plains of India

In the present investigation, the long-term effect of pulse crop inclusion in the maize-wheat rotation was assessed for the nutrient availability and soil-plant nutrient cycling under different nutrient management practices. Including pulses in the maize-wheat rotation improved soil organic carbon (SOC) and plant available macronutrients being higher in maize-wheat-mungbean rotation. Inclusion of mungbean to maize-wheat rotation enhanced the nitrogen (33.9%), phosphorus (46.4%), potassium (36.3%), and sulphur (55.5%) uptake in maize crop; likewise, alternate-year chickpea inclusion increased the uptake of these nutrients by 18.2, 19.1, 21.7, 32.1%, respectively. Inorganic fertilization maintained the positive annual balance of nitrogen, phosphorus, and zinc. By contrast, the nutrient balance under organic nutrient management was mostly negative. The magnitude of negative balance of potassium and sulphur was higher in inorganic than that of organic nutrient management. The low nutrient supply (particularly nitrogen) in organic fertilization largely inhibited the yield of cereal crops but not that of pulses. In view of this, the inclusion of pulses in the cereal-cereal systems could cause substantial improvement in soil fertility and sustainability in Indo-Gangetic plains. We infer that supply of nutrients like nitrogen and phosphorus in organic, and potassium and sulphur in recommended inorganic fertilization merit special attention.     

Physical properties and moisture retention characteristics of some nigerian soils

Measurements were made of physical characteristics of 119 samples from 23 profiles derived from two parent materials in Nigeria. The laboratory analyses included texture, plasticity and shrinkage characteristics, and a range of soil moisture constants including saturation point and moisture retention at various suctions. Simple and multiple correlation coefficients and regression analyses were conducted to investigate the possibilities of obtaining estimates of soil moisture retention from the textural analysis. Clay and sand contents are correlated with various soil moisture constants. The textural analysis may therefore be used to estimate moisture holding capacity at different suctions for these and similar soils with a predominantly uniform clay mineralogy, dominated by kaolinite and sesquioxides. Moisture retention curves indicate that the “field capacity” for most of these soils is better estimated at 60 or 100 cm of water suction rather than at 0.3 bar. A plot of the pF curves indicated only slight differences between moisture retention at 2 or 3 bar suction and at 15 bar suction.     

Determining soil quality indicators by factor analysis

Soil quality indicators (SQIs) can be used to evaluate sustainability of land use and soil management practices in agroecosystems. The objective of this study was to identify appropriate SQI from factor analysis (FA) of five treatments: no-till corn (Zee mays) without manure (NT), no-till corn with manure (NTM), no-till corn–soybean (Glycine max) rotation (NTR), conventional tillage corn (CT), and meadow (M) in Coshocton, Ohio. Soil properties were grouped into five factors (eigenvalues > 1) for the 0–10 cm depth as: (Factor 1) water transmission, (Factor 2) soil aeration, (Factor 3) soil pore connection 1, (Factor 4) soil texture and (Factor 5) moisture status. Factor 2 was the most dominant, with soil organic carbon (SOC) the most dominant measured soil attribute contributing to this factor. For the 10–20 cm depth, factors identified were: (Factor 6) soil aggregation, (Factor 7) soil pore connection 2, (Factor 8) soil macropore, and (Factor 9) plant production. At 10–20 cm depth, Factor 6 was most dominant with SOC the most dominant measured soil attribute. Management × sample and slope position × sample interactions were significant among some factors for both depths. Overall, SOC was the most dominant measured soil attribute as a SQI for both depths. Other key soil attributes were field water capacity, air-filled porosity, pH and soil bulk density for the 0–10 cm depth, and total N and mean weight diameter of aggregates for the 10–20 depth. Therefore, SOC could play an important role for monitoring soil quality.     

Soil restorative effects of mulching on aggregation and carbon sequestration in a Miamian soil in central Ohio

Soils play a key role in the global carbon cycle, and can be a source or a sink of atmospheric carbon (C). Thus, the effect of land use and management on soil C dynamics needs to be quantified. This study was conducted to assess: (1) the role of aggregation in enhancing soil organic carbon (SOC) and total soil nitrogen (TSN) concentrations for different mulch rates, (2) the association of SOC and TSN with different particle size fractions, and (3) the temporal changes in the SOC concentration within aggregate and particle size fractions with duration of mulching. Two experiments were initiated, one each in 1989 and 1996, on a Crosby silt loam (Aeric Ochraqualf or Stagnic Luvisol) in central Ohio. Mulch treatments were 0, 8, and 16 Mg ha⁻¹ yr⁻¹ without crop cultivation. Soil samples from 0–5 cm and 5–10 cm depths were obtained in November 2000; 4 and 11 years after initiating the experiments. Mulch rate significantly increased SOC and TSN concentrations in the 0–5 cm soil layer only. The variation in the SOC concentration attributed to the mulch rate was 41 per cent after 4 years of mulching and 52 per cent after 11 years of mulching. There were also differences in SOC and TSN concentrations among large aggregate size fractions, up to 2 mm size after 4 years and up to 0ċ5 mm after 11 years of mulching. There were also differences in SOC and TSN concentrations among particle size fractions. Variation in the SOC concentration in relation to particle size was attributed to clay by 45–51 per cent, silt by 34–36 per cent, and to sand fraction by 15–19 per cent. Bulk of the TSN (62–67 per cent) was associated with clay fraction and the rest was equally distributed between silt and sand fractions. The enrichment of SOC and TSN concentrations in the clay fraction increased with depth. The C:N ratio was not affected by the mulch rate, but differed significantly among particle size fractions; being in the order of sand >silt >clay. Copyright © 2003 John Wiley & Sons, Ltd.     

Axle load and tillage effects on the shrinkage characteristics of a Mollic Ochraqualf in northwest Ohio

Cracking due to soil shrinkage is a complex process whose effect on soil properties, crop growth and water quality are not adequately understood. The intensity of cracking depends on soil characteristics and management. The effect of three axle loads and three tillage methods on shrinkage characteristics and cracking behavior were studied for a heavy-textured lake bed soil in northwest Ohio. The three axle load treatments were 0, 10 and 20 Mg, and the three tillage treatments were no till (NT), chisel plowing (CP) and moldboard plowing (MP). Cracking area increased from 1.75% in July to 12.27% in September, was maximum in the NT treatment, and increased with increase in axle load. The no till and 30 Mg axle load caused significantly higher cracking than other axle load and tillage treatment combinations. Shrinkage of compressed soil cores under laboratory conditions showed that a bulk density of 1.5 Mg/m³ had the lowest total shrinkage volume. A combination of no till and heavy axle load increased the cracking area and accentuated adverse effects on soil structure.     

Effects of tillage methods on physical and hydrological properties of a tropical Alfisol

The results of a long term study of the effects of no-tillage and conventional plowing with or without crop residue mulch on soil physical and hydrological properties and on yield of maize are reported for an Alfisol in southwest Nigeria. After 10 years, total porosity of the 0 to 10 cm depth were 48, 50, 39 and 39 percent for no-tillage without mulch (NT-M), no-tillage with mulch (NT+M), conventional tillage without mulch (CT-M) and conventional tillage with mulch (CT+M) respectively. Saturated hydraulic conductivity for the same depth were 753, 750, 183 and 908 cm/day for NT-M, NT+M, CT-M and CT+M respectively. Laboratory measured moisture retention at 50 cm suction for the same depth was 30, 29, 19 and 28 percent. The maximum available water storage capacity for the surface 40 cm layer was 59 and 41 mm for no-tillage compared with 44 and 33 mm for the conventional tillage treatments with and without mulch, respectively. Grain yield increased at the rate of 0.17 t/ha for 1 mm increase in the available water capacity between the range of 33 and 59 mm.     

Cell mediated immune response of chicks following fowl adenovirus type-1 infection.

Cellular immune response of 6-week-old chickens infected with fowl adenovirus type-1 was evaluated by both in vivo and in vitro assay. In vitro assay, enumerating peripheral T lymphocyte by alphanaphthyl acetate esterase staining, revealed that cellular immunity appeared as early as 1 week post-infection and was maintained up to 5 weeks post-infection. In vivo assay by phytohaemagglutin skin test showed cellular immunity until 2 weeks post-infection. Thereafter no immunity was observed by this assay.     

Soaking Induced Changes in Chemical Composition,Glycemic Index and Starch Characteristics of Basmati Rice

An attempt was made to determine the qualitative changes in basmati rice(Pusa Basmati 1121, PB1121) during soaking at 40 ℃ to 80 ℃. Soaking temperature had significant effect(α = 0.01) on chemical composition, glycemic index and starch characteristics of rice. Starch content, apparent amylose content, crude protein content and crude fat content in un-soaked rice were found to be 73.24%, 27.26%, 8.79% and 2.56%, respectively, but differences in these traits were observed after soaking. Amylose to amylopectin ratio(Am/Ap) decreased from 0.59 to 0.52(soaked at 80 ℃). Crude fibre and crude ash contents increased after soaking. The mineral composition(K, P, S, Ca, Mg, Mn, Fe, Cu and Zn) in soaked rice was found to be 16.46% higher than un-soaked rice at the same degree of polishing. Glycemic index of un-soaked rice was found to be 58.41, but decreased to 54.31 after soaking at 80 ℃. Pasting properties, scanning electron microscope images, and X-ray diffractograms suggested partial gelatinization of starch in the temperature range of 60 ℃ to 80 ℃. Based on qualitative changes in rice(apparent amylose content, Am/Ap ratio and crystallinity rate), it was concluded that intermediate soaking temperatures(60 ℃ to 70 ℃) would be useful for soaking of PB1121.     

Soil organic matter and CO2 emission as affected by water erosion on field runoff plots

Soil organic carbon (SOC) is an important component of the global carbon cycle. Its dynamics depends upon various natural and anthropogenic factors including soil erosion. A study on Miamian silty clay loam soil in central Ohio was conducted to investigate the effect of soil erosion on SOC transport and mineralization. Runoff plots 10, 20 and 30 m long on a 7% slope under natural rainfall were used. Total soil loss, evolution of CO₂ from the displaced aggregates of various fractions, and total SOC concentrations were determined. It was shown that the primary ways of SOC loss resulted from two processes: 1) mechanical preferential removal of SOC by overland flow and 2) erosion-induced mineralization. Significant amounts of SOC mobilized by erosion at the upper part of the slope during the season (358 kg ha^? 1) could be lost to the atmosphere within 100 days (15%) and transported off site (44%). Breakup of initial soil aggregates by erosive forces was responsible for increased CO₂ emission. During the initial 20 days of incubation the amount of CO₂ released from coarse size sediment fractions (0.282 g C kg^? 1 soil d^? 1) was 9 times greater than that in fine fractions (0.032 g C kg^? 1 soil d^? 1) due to the greater initial amount of SOC and its exposure to the environment. Sediment size distribution as well as its residence time on the site was the primary controllers of CO₂ loss from eroded soil.