Salinity and nutrient distribution in soil profiles of long-term crop rotations

1994 ◽  
Vol 74 (2) ◽  
pp. 229-234
Author(s):  
G. J. Beke ◽  
H. H. Janzen ◽  
T. Entz
Keyword(s):  
Root Zone ◽  
Soil Depth ◽  
Crop Rotations ◽  
Research Station ◽  
Nitrate N ◽  
Cropping Sequence ◽  
Extractable P ◽  
The Impact ◽  
Semi Arid

The effect of cropping systems on salt and nutrient movement in soil has been studied mainly at relatively short-term (< 20 yr) experimental sites or at commercial sites without documented history. This study investigated the impact of two similar, unfertilized, long-term crop rotation experiments, differing in duration and experimental design, on soil EC (salinity), sodium adsorption ratio (SAR), nitrate-N, and extractable-P distributions in semi-arid southern Alberta. The experiments, established in 1911 and 1951 at the Lethbridge Research Station on moderately well drained soils, included continuous spring wheat (Triticum aestivum L.) fallow-wheat-wheat and fallow-wheat cropping sequences. Regardless of length of experiment or cropping sequence, the salinity and SAR values increased with soil depth. Leaching of salts had occurred to a minimum depth of 150 cm, depending on the nature of the parent material and soil-drainage volumes. Within the 90- to 150-cm depth, most salt leaching had taken place under the fallow-wheat rotation and least under the continuous-wheat cropping sequence. Downward movement of nitrate-N generally peaked in the lower root zone, regardless of cropping system or duration of the experiment. Deep leaching of nitrate-N had occurred in the fallow-wheat soil. Movement of extractable P was restricted to the 0- to 30-cm depth. Significant deep leaching of salts had taken place over the 35-yr period of the 1951 experiment whereas the longer, 75-yr period of the 1911 experiment was required to cause significant deep leaching of nitrate-N and of extractable P movement in the 0- to 30-cm depth. Key words: Dryland crop rotations, summerfallow, semi-arid region, soil salinity, soil nitrate and phosphate

scholarly journals Soil management and production of alfisols in the semi-arid tropics. IV.* Simulation of decline in productivity caused by soil erosion

Soil Research ◽  
1996 ◽  
Vol 34 (1) ◽  
pp. 127 ◽  
Author(s):  
M Littleboy ◽  
AL Cogle ◽  
GD Smith ◽  
KPC Rao ◽  
DF Yule
Keyword(s):  
Soil Erosion ◽  
Crop Production ◽  
Management Practices ◽  
Soil Depth ◽  
Management Options ◽  
Yield Decline ◽  
Initial Soil ◽  
The Impact ◽  
Semi Arid

Maintenance of a productive soil base by minimizing soil erosion is vital to long-term crop production. In this study, a modelling approach is used to estimate the effects of soil erosion on productivity for a sorghum cropping system on an Alfisol in the semi-arid tropics of India. Predictions of erosion, runoff and yield decline due to erosion, for variations in initial soil depth, slope, tillage strategy and amendment treatment, are presented. On average, soil depth decreased by 0.91 cm/year at Hyderabad for a 10% slope, 80 cm initial soil depth, shallow tillage at planting and no surface amendment. Rates of soil removal and subsequent yield decline were higher for shallower soils, steeper slopes and if management practices provided less surface cover during the crop. The productive life of the soil was less than 91 years for some soil depths, slope and management combinations. For other combinations, significant yield decline was predicted after 91 years of cropping. The quantification of erosion-productivity relationships allows us to identify regions with a higher risk of degradation from soil erosion and to estimate the impact of various management options on long-term sustainability. Models provide a basis to focus research and a means of assessing alternative management strategies to preserve long-term production.* Part III, Aust. J. Soil Res. 1996, 34, 113–125.

Soil acidification and the carbon cycle in a cropping soil of north-eastern Victoria

Soil Research ◽  
1998 ◽  
Vol 36 (2) ◽  
pp. 273 ◽  
Author(s):  
W. J. Slattery ◽  
D. G. Edwards ◽  
L. C. Bell ◽  
D. R. Coventry ◽  
K. R. Helyar
Keyword(s):  
Soil Depth ◽  
Organic C ◽  
Soil Layers ◽  
Soil C ◽  
Soil Zone ◽  
North Eastern ◽  
Soil Buffering ◽  
The Impact ◽  
Total Organic C

Changes in soil organic matter were determined for a long-term (1975–95) experiment at the Rutherglen Research Institute in north-eastern Victoria. The crop rotations in this experiment were continuous lupins (LL) and continuous wheat (WW). The soil at this site was a solodic or Yellow Dermosol with a soil pH of 6·08 (pH in 0·01 М CaCl2 1 : 5) in 1975 in the surface 10 cm, which had declined by 0·8 and 1·5 pH units for WW and LL, respectively, in the 0–20 cm soil zone by 1992. Acidification rates decreased with increasing soil depth. The acidification rate in the 0–60 cm soil zone was 12·5 kmol(H+)/ha·year for the LL rotation and 4·6 kmol(H+)/ha·year for the WW rotation. The amount of CaCO3 required to neutralise the acidification of wheat-lupin rotations as calculated in this paper was up to 3·8 t/ha ·10 years for a WLWL rotation or 3 ·3 t/ha ·10 years for a WWL rotation; these amounts are significantly higher than previously reported rates. In this paper, we calculate the impact of changes in soil carbon (C) status over time, and therefore soil buffering, on the rates of acidification in incremental soil layers to a depth of 60 cm. Total organic C for these rotations in 1992 was 1·12% for WW and 1·17% for LL in the 0–10 cm soil zone. An investigation of the humic and fulvic acid fractions of these 2 rotations to a depth of 60 cm showed that the LL rotation had significantly higher (P < 0·05) C at depth than the WW rotation. Acidification due to the net decrease in soil C over the 15-year study period plus acidification due to the alkali removed in the seed was calculated to be –4·88 kmol(H+)/ha·year for the LL rotation and –6·52 kmol(H+)/ha·year for the WW rotation.

scholarly journals On the factors influencing surface-layer energy closure and their seasonal variability over the semi-arid Loess Plateau of Northwest China

2012 ◽  
Vol 16 (3) ◽  
pp. 893-910
Author(s):  
X. Xiao ◽  
H. C. Zuo ◽  
Q. D. Yang ◽  
S. J. Wang ◽  
L. J. Wang ◽  
...  
Keyword(s):  
Surface Layer ◽  
Energy Balance ◽  
Atmospheric Turbulence ◽  
Loess Plateau ◽  
Turbulence Intensity ◽  
Source Area ◽  
Northwest China ◽  
The Impact ◽  
Semi Arid

Abstract. The energy observed in the surface layer, when using eddy-covariance techniques to measure turbulent fluxes, is not balanced. Important progress has been made in recent years in identifying potential reasons for this lack of closure in the energy balance, but the problem is not yet resolved. In this paper, long-term data that include output of tower, radiation, surface turbulence flux and soil measurement collected from September 2006 to August 2010 in the Semi-Arid Climate Change and Environment Observatory, Lanzhou University, in the semi-arid Loess Plateau of Northwest China, were analysed, focusing on the seasonal characteristics of the surface energy and the factors that have impact on the energy balance closure (EBC). The analysis shows that (1) the long-term observations are successful; the interaction between the land and the atmosphere in semi-arid climates can be represented by the turbulent transport of energy. In addition, even though the residual is obvious, this suggests that the factors that impact the EBC are stable, and their seasonal variations are identical. The analysis also shows that (2) four factors have obvious impact on the EBC: the diverse schemes for surface soil heat flux, the flux contribution from the target source area, the low-frequency part of the turbulence spectra, and the strength of atmospheric turbulence motion. The impact of these four factors on the EBC are similar in all seasons. Lastly, the results indicate that (3) atmospheric turbulence intensity is a very important factor in terms of its impact on the EBC. The relative turbulence intensity, RIw, characterises the strength of atmospheric turbulence motion, and is found to exert a noticeable impact on the EBC; in all seasons, the EBC is increased when the relative turbulence intensity is enlarged.

scholarly journals Savanna burning and the assessment of long-term fire experiments with particular reference to Zimbabwe

2008 ◽  
Vol 32 (6) ◽  
pp. 611-634 ◽  
Author(s):  
Peter A. Furley ◽  
Robert M. Rees ◽  
Casey M. Ryan ◽  
Gustavo Saiz
Keyword(s):  
Stocking Density ◽  
Basal Area ◽  
Research Station ◽  
Herbaceous Plant ◽  
Burned Areas ◽  
Vegetation Surveys ◽  
Savanna Burning ◽  
The Impact ◽  
Fire Experiments

Long-term fire experiments in savannnas are rare, given the difficulties and demands of operation. Controlled fire experiments date from colonial times in West Africa, although the largest and best-known is located in the Kruger National Park, South Africa. The achievements of these experiments are assessed from examples in Africa, South America and Australia. A less well-known experiment in Zimbabwe was sited at the Marondera Grassland Research Station and ran from 1953 to 1991. Some of the preliminary results on the impact of fire on vegetation are analysed and compared with further vegetation surveys in 2007. Studies on tree growth in this miombo savanna woodland indicate that the plots burned at three- and four-year intervals recovered to greater mean heights than the unburned control plots. There was no significant variation between treatments, suggesting that the few trees that did survive in the frequently burned plots were large specimens. Brachystegia and Julbernadia dominated the plots throughout and after the experiment. Basal area and stocking density were highest in the four-yearly burned plots but there was a high variability throughout the experiment, suggesting that many trees may have attained heights and bark thicknesses sufficient to protect from fire damage. Fire also affected the composition of the herbaceous plant community, but not the number of species. By the end of the experiment some grass and sedge species had flourished while others revealed greater susceptibility to fire, and fire-tolerant species predominated in the most frequently burned areas. The experimental design appeared to cope well with the variability between plots and indicated the soundness of the initial design and its implementation.

scholarly journals Strategic directions of increase of bean production in Ukraine

2021 ◽  
pp. 70-83
Author(s):  
V. I. Sichkar
Keyword(s):  
Soil Quality ◽  
Root Zone ◽  
Essential Amino Acids ◽  
Crop Rotations ◽  
Total Biomass ◽  
High Quality ◽  
Legume Seeds ◽  
Subsequent Crop ◽  
The Impact

Goal. Based on the results to substantiate the need for a significant increase in legume crops in Ukraine on the basis of analysis of food and feed indicators of their seeds, the impact on soil quality and the environment. Material and methods. Field – determination of features of growth and development of plants, elements of seed productivity; biometric and measuring-weight – accounting of yield and total biomass; biochemical – determination of protein, fat and other components of seeds; statistical – variation, regression and analysis of variance. Results and discussion. The significant nutritional value of legume seeds, which is rich in high-quality protein with a high content of essential amino acids, isoflavones, essential micronutrients, is substantiated. It is distinguished by high taste, quickly swells and boils, has a pleasant aroma. This group of crops is able to fix nitrogen from the air, provide for their own needs and leave a significant amount of it in the soil for subsequent crop rotations. Legumes should be considered in the crop rotation system together with winter wheat as fallow crops. Their synergistic effect on subsequent crop rotations is explained by the peculiarity of the microflora of the root zone, where symbiotic and free-living bacteria are concentrated. Observations indicate the need to increase crops of pea, chickpea and lentil in Ukraine, as there are all the necessary conditions - adapted to insufficient moisture varieties, developed technology for their cultivation, accumulated positive experience for obtaining high yields. Conclusions. Based on our own results and analysis of the experience of many countries around the world revealed the importance of legumes for our country. Their role in providing high-quality food, improving soil quality, increasing the country’s export potential is noted

Nitrate accumulation under cropping in the Ferrosols of Far North Queensland wet tropics

Soil Research ◽  
2001 ◽  
Vol 39 (2) ◽  
pp. 329 ◽  
Author(s):  
V. Rasiah ◽  
J. D. Armour
Keyword(s):  
Management Practices ◽  
Root Zone ◽  
Nitrate Accumulation ◽  
Retention Capacity ◽  
Soil Matrix ◽  
Far North ◽  
Nitrate N ◽  
Wet Tropics ◽  
Crop Root

Recent research on the fate of applied fertiliser N in the Ferrosols of the wet tropics of Far North Queensland (FNQ) has shown that the nitrate leaching below the crop root-zone is a major pathway of N loss from paddocks. Information on the fate of this nitrate is essential to develop best N fertiliser management practices and for the long-term sustainability of land and water resources. Because of the ability of Ferrosols to adsorb anions in the soil matrix, it was speculated that the leached nitrate may be accumulating at depth in the Ferrosol profiles. The objectives of this study were to (i) verify whether the leached nitrate has been accumulating in the Ferrosols under the major cropping systems in the Johnstone River Catchment (JRC) of FNQ, and (ii) provide preliminary estimates for nitrate retention capacity of the Ferrosols. Soil cores to a depth of 10 m were taken from under sugarcane (Saccharum officinarum-S), banana (Musa (AAA group, Cavendish subgroup) cv. Williams), dairy pasture, and rainforest in JRC during August 1995. The cores were segmented at 0.5-m depth increments and soil samples were analysed for nitrate- and ammonium-N, cation- (CEC) and anion- (AEC) exchange capacities, pH, Ca2+ , Mg 2+ , K + , Na + , and Cl – . Nitrate-N concentration under sugarcane was as high as 33 mg/kg, compared with 6.9 mg/kg for banana, 0.3 mg/kg under rainforest, and that under pasture was below detection limit. Nitrate-N load in the top 10 m of the profiles under sugarcane ranged from 345 to 1875 kg nitrate-N/ha compared with 145 kg/ ha for banana, and 21 kg/ha under rainforest. Most of the nitrate accumulation was found between 2 and 8 m, i.e. well below the crop root-zone. From 7% to 70% of the nitrate that leached below crop root-zone was retained at depths >1 m. In general, Cl – and total cation (TC = sum of Ca2+ , Mg 2+ , K + , and Na + ) concentrations in the profiles under cropping were higher than those under rainforest, and the pH under sugarcane was more acidic. Simple correlation analysis indicated associations existed between the accumulated nitrate and Cl – , pH, AEC, or TC. The estimated nitrate holding capacity of the Ferrosols ranged from 17 to 32 t N/ha. The results show that large quantities of the nitrate that leached below crop root-zone have accumulated at depth under long-term sugarcane and banana cropping in the Ferrosols of FNQ.

Impacts of fire on soil organic carbon stocks in a grazed semi-arid tropical Australian savanna: accounting for landscape variability

2014 ◽  
Vol 36 (4) ◽  
pp. 359 ◽  
Author(s):  
D. E. Allen ◽  
P. M. Bloesch ◽  
R. A. Cowley ◽  
T. G. Orton ◽  
J. E. Payne ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Spatial Variability ◽  
Management Practices ◽  
Soil Depth ◽  
Carbon Stocks ◽  
Soil Organic Carbon Stocks ◽  
Semi Arid ◽  
Soc Stocks

Fire and grazing are commonplace in Australian tropical savannas and the effects of these management practices on soil organic carbon stocks (SOC) is not well understood. A long-term (20 years) experiment studying the effects of fire on a grazed semi-arid tropical savanna was used to increase this understanding. Treatments, including frequency of fire (every 2, 4 and 6 years), season of fire [early (June) vs late (October) dry season] and unburnt control plots, were imposed on Vertosol grassland and Calcarosol woodland sites, which were grazed. Additionally long-term enclosures [unburnt (except the Calcarosol in 2001) and ungrazed since 1973] on each soil type adjacent to each site were sampled, although not included in statistical analyses. SOC stocks were measured to a soil depth of 0.3 m using a wet oxidation method (to avoid interference by carbonates) and compared on an equivalent soil mass basis. Significant treatment differences in SOC stocks were tested for, while accounting for spatial background variation within each site. SOC stocks (0–0.3 m soil depth) ranged between 10.1 and 28.9 t ha–1 (Vertosol site) and 20.7 and 54.9 t ha–1 (Calcarosol site). There were no consistent effects of frequency or season of fire on SOC stocks, possibly reflecting the limited statistical power of the study and inherent spatial variability observed. Differences in the response to frequency and season of fire observed between these soils may have been due to differences in clay type, plant species composition and/or preferential grazing activity associated with fire management. There may also have been differences in C input between treatments and sites due to differences in the herbage mass and post-fire grazing activity on both sites and changed pasture composition, higher herbage fuel load, and a reduction in woody cover on the Vertosol site. This study demonstrated the importance of accounting for background spatial variability and treatment replication (in the absence of baseline values) when assessing SOC stocks in relation to management practices. Given the absence of baseline SOC values and the potentially long period required to obtain changes in SOC in rangelands, modelling of turnover of SOC in relation to background spatial variability would enable management scenarios to be considered in relation to landscape variation that may be unrelated to management. These considerations are important for reducing uncertainty in C-flux accounting and to provide accurate and cost-effective methods for land managers considering participation in the C economy.

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