Soil nitrogen availability in the cereal zone of South Australia .1. Soil organic carbon, total nitrogen, and nitrogen mineralisation rates

Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 937 ◽  
Author(s):  
ZH Xu ◽  
JN Ladd ◽  
DE Elliott

Assessments of soil nitrogen (N) availability were undertaken using soils sampled at 0-10 and 10-20 cm depths from 123 experimental sites where the responses of cereal crops to N fertilisers were tested, throughout the cereal zone of South Australia. Rates of N mineralisation and percentage N mineralisation, as determined by a laboratory aerobic incubation method, were related to soil properties. Mineralisable N (N mineralised during a Li-week incubation) of 0-10 cm soil varied from 14 to 121 kg N/ha with a median of 50 kg N/ha, and that of 10-20 cm soil, from 5 to 42 kg N/ha (median 19 kg N/ha). Mineralisable N in 0-10 cm soil accounted for 90% of total mineralisable N in 0-20 cm soil. The percentages of N mineralised were generally higher in 0-10 cm soil (0.8-12.5%, median 3.4%) than in 10-20 cm soil (0.4-8.3%, median 2.3%). Soil organic carbon (OC) and total N could be well estimated from each other, and fron! soil pH, bulk density, and held capacity, with coefficients of determination (R2) ranging from 0.64 to 0.78. Overall, either mineralisable N or percentage N mineralisation rate in the surface soils could be well estimated from soil OC, total N, C to N ratio, bulk density, field capacity, and pH (R2, 0.78-0.86 for mineralisable N, and 0.67-0.91 for percentage N mineralisation rate).


1995 ◽  
Vol 31 (3) ◽  
pp. 333-344 ◽  
Author(s):  
G. Webert ◽  
V. Chude ◽  
J. Pleysier ◽  
S. Oikeh

SummaryNitrate-nitrogen was analysed over two cropping seasons in 57 farmers' fields in the northern Guinea savanna of Nigeria. Differences between fields were at least five-fold and often ten-fold irrespective of fertilization rates. Average concentrations were highest at the beginning of the rainy season. Loamy soils had a later peak for nitrate release and maintained high concentrations for a longer period after the start of the rains than the more sandy soils. Nitrate-N was not correlated with soil organic carbon or total nitrogen content. Grain yield of maize was closely associated with nitrate-N in the soil but not with organic carbon or total N. Four patterns of nitrate-N release over the season could he differentiated using cluster analysis. Soil texture, soil pH, soil organic carbon, stover management and cropping history contributed most to a differentiation of the four cluster groups in a discriminant model. There was wide variability in the inherent soil-nitrate level and in its importance in explaining differences in yield among farmers' fields. The development of technologies resulting in improved nitrogen availability or better nitrogen utilization should be based on research of inherent soil processes. For the transfer of such technologies, recommendation domains should be defined based on different native patterns of soil-nitrogen availability.



Soil Research ◽  
2004 ◽  
Vol 42 (7) ◽  
pp. 719 ◽  
Author(s):  
M. T. Moroni ◽  
P. J. Smethurst ◽  
G. K. Holz

Several soil analyses were used to estimate available N in surface soils (0–10 cm) over a 2-year period at 5 sites that supported 1- to 4-year-old Eucalyptus nitens plantations, and once in subsoils (10–120 cm) at 3 of these sites. Soils were derived from basalt (1 site previously pasture, 1 Pinus radiate, and 2 native forest) or siltstone (previously native forest). Soil analyses examined were total N, total P, total C, anaerobically mineralisable N (AMN), hot KCl-extractable N (hot KCl-N), and NH4+ and NO3– in soil solution and KCl extracts. AMN, KCl-extractable NH4+ and NO3–, and soil solution NH4+ and NO3– varied considerably with time, whereas hot KCl-N, total N, total P, and total C were temporally stable except for a gradual decline in total C with time at one site. Only total P was correlated with net N mineralisation (NNM) across all sites (r2 = 0.91, P < 0.05, n = 5). At 2–3 years after planting, soil solution and KCl-extractable NO3– dropped below 0.1 mm N and 1 μg N/g soil, respectively, at sites with NNM ≤24 kg N/ha.year (n = 3). Sites with NNM ≤24 kg N/ha.year also had ≤0.8 Mg P/ha. Although concentrations of indices of soil N availability decreased with depth, the contribution of subsoil (10–120 cm depth) to total profile N availability was estimated to be at least twice that of the top 10 cm. At an ex-pasture site, high concentrations of mineral N were found at 75–105 cm depths (KCl-extractable N, 289.3 μg N/g soil; 2.8 mm mineral N in soil solution), which may have become available to plantations as their root systems developed.



2011 ◽  
Vol 91 (4) ◽  
pp. 493-501 ◽  
Author(s):  
K. Liu ◽  
A. M. Hammermeister ◽  
P. R. Warman ◽  
C. F. Drury ◽  
R. C. Martin

Liu, K., Hammermeister, A. M., Warman, P. R., Drury, C. F. and Martin, R. C. 2011. Assessing soil nitrogen availability in contrasting cropping systems at the end of transition to organic production. Can. J. Soil Sci. 91: 493–501. Quantifying soil nitrogen (N) availability at the end of a transition period for converting conventional fields to organic fields could enhance N management during the subsequent organic crop production phase. Soil total N (Ntot), KCl extractable N (KCl N) and potentially mineralizable N (No) were determined at the end of a 3-yr transition period. A complementary greenhouse ryegrass N bioassay was conducted using soils collected from the treated field plots. The field experiment consisted of six cropping systems comprising two N inputs (legume-based vs. manure-based) and three forage cropping treatments (0, 1 or 2 yr of forage in 4-yr rotations). The N input treatments consisted of alfalfa meal in the legume-based cropping system (LBCS) and composted beef manure in the manure-based cropping system (MBCS). Orthogonal contrasts suggested no differences in Ntot or KCl N either between LBCS and MBCS or between no-forage and forage cropping systems. However, in the greenhouse study, high cumulative N inputs in the MBCS resulted in significantly higher ryegrass N uptake and potentially mineralizable soil N than in the LBCS. Ryegrass N uptake ranged from 101 to 139 kg ha−1, which should be an adequate N supply for the succeeding potato crop. In the greenhouse, a ryegrass N bioassay effectively identified the differences in soil N availability. Ryegrass N uptake was linearly related to cumulative soil amendment N inputs but had no apparent relationship with N o. A systems approach provided a good assessment of N availability at the end of the transition period to organic production.



2016 ◽  
Vol 3 (2) ◽  
Author(s):  
Aradhna Kumari ◽  
Santosh Kumar Singh

Conventional agriculture can result in loss of organic matter (OM), resulting in degradation of cultivated soil. A study was conducted to assess the impact of different tillage treatments in rice and wheat cropping system on soil organic carbon and nitrogen pool. The experiment was carried out in split plot design with four main plot treatments viz. P (direct dry seeding by zero till drill), P 1 2 (direct seeding of sprouted rice in puddle condition), P (hand transplanting) and P (transplanting 3 4 by self-propelled rice trans planter) while the sub plot treatment (for wheat) included T 1 (conventional sowing), T (bed planting), T (strip till drilling) and T (zero till drilling). Significant 2 3 4 variations in SOC and soil nitrogen pool were observed in wheat tillage treatments for D (0-10cm) 1 soil depth. The T and T treatments had significantly higher values of SOC pool as compared to T . 4 3 1 Similar trend was also observed for soil nitrogen. Rice tillage treatments did not have any significant impact on SOC and soil nitrogen at D or subsequent depths. The summarized depths 0- 1 30 and 0-60 cm did not show any impact of the tillage treatments on SOC or soil nitrogen pools.In rice tillage treatments, SOC pool ranged from 26.06 Mg/m3 (P ) to 27.61 Mg/m3 (P ) while the range 4 1 for wheat tillage treatment was 26.30 Mg/m3 (T ) to 26.75 Mg/m3 (T ). At D depth soil N pool was 4 1 1 found to be statistically higher for T and T tillage treatments in wheat, whereas T tillage treatment 3 4 2 was found to be statistically at par with T . This is because of the presence of higher amount of SOM 1 in T and T . A high and positive correlation between SOC and total N was observed because most of 3 4 the nitrogen present in soil is in organic form.



2021 ◽  
Vol 13 (13) ◽  
pp. 6997
Author(s):  
Dembe Maselesele ◽  
John B.O. Ogola ◽  
Romeo N. Murovhi

Poor soil fertility caused mainly by low and declining soil organic carbon is one of the major constraints limiting crop productivity in tropical and subtropical regions of South Africa. We evaluated the effect of macadamia husk compost (MHC) on selected chemical and physical properties of a sandy loam soil in NE South Africa in two successive seasons. The treatments, laid out in randomised, complete block design and replicated four times, were: (i) zero control, (ii) inorganic fertilizer (100:60:60 NPK Kg ha−1), (iii) MHC at 15 t ha−1, and (iv) MHC at 30 t ha−1. Soil bulk density; water holding capacity; soil pH; electrical conductivity (EC); organic carbon; total N; and available P, K, Ca, Mg, Al, Zn, and Cu were determined at 0–15 cm soil depth. Macadamia husk compost application decreased bulk density and increased water holding capacity. MHC and inorganic fertilizer increased soil pH, organic carbon, total N, C:N ratio, available P, exchangeable cations, and micronutrients but the effect was more pronounced under MHC treatments in both seasons. The positive effect of MHC on soil physicochemical properties was associated with an increase in soil organic carbon due to MHC application; hence, MHC may offer a sustainable option of increasing soil productivity, particularly in areas characterised by low SOC.



Water ◽  
2017 ◽  
Vol 9 (3) ◽  
pp. 208 ◽  
Author(s):  
Zhiping Fan ◽  
Zhihua Tu ◽  
Fayun Li ◽  
Yanbin Qin ◽  
Dongzhou Deng ◽  
...  


2014 ◽  
Vol 11 (6) ◽  
pp. 1649-1666 ◽  
Author(s):  
X. P. Liu ◽  
W. J. Zhang ◽  
C. S. Hu ◽  
X. G. Tang

Abstract. The objectives of this study were to investigate seasonal variation of greenhouse gas fluxes from soils on sites dominated by plantation (Robinia pseudoacacia, Punica granatum, and Ziziphus jujube) and natural regenerated forests (Vitex negundo var. heterophylla, Leptodermis oblonga, and Bothriochloa ischcemum), and to identify how tree species, litter exclusion, and soil properties (soil temperature, soil moisture, soil organic carbon, total N, soil bulk density, and soil pH) explained the temporal and spatial variation in soil greenhouse gas fluxes. Fluxes of greenhouse gases were measured using static chamber and gas chromatography techniques. Six static chambers were randomly installed in each tree species. Three chambers were randomly designated to measure the impacts of surface litter exclusion, and the remaining three were used as a control. Field measurements were conducted biweekly from May 2010 to April 2012. Soil CO2 emissions from all tree species were significantly affected by soil temperature, soil moisture, and their interaction. Driven by the seasonality of temperature and precipitation, soil CO2 emissions demonstrated a clear seasonal pattern, with fluxes significantly higher during the rainy season than during the dry season. Soil CH4 and N2O fluxes were not significantly correlated with soil temperature, soil moisture, or their interaction, and no significant seasonal differences were detected. Soil organic carbon and total N were significantly positively correlated with CO2 and N2O fluxes. Soil bulk density was significantly negatively correlated with CO2 and N2O fluxes. Soil pH was not correlated with CO2 and N2O emissions. Soil CH4 fluxes did not display pronounced dependency on soil organic carbon, total N, soil bulk density, and soil pH. Removal of surface litter significantly decreased in CO2 emissions and CH4 uptakes. Soils in six tree species acted as sinks for atmospheric CH4. With the exception of Ziziphus jujube, soils in all tree species acted as sinks for atmospheric N2O. Tree species had a significant effect on CO2 and N2O releases but not on CH4 uptake. The lower net global warming potential in natural regenerated vegetation suggested that natural regenerated vegetation were more desirable plant species in reducing global warming.



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