Environmental Impact of Rotationally Grazed Pastures at Different Management Intensities in South Africa

Nitrogen fertilization, irrigation and concentrate feeding are important factors in rotational pasture management for dairy farms in South Africa. The extent to which these factors affect environmental efficiency is subject to current and intense debate among scientists. A three-year field study was conducted to investigate the yield response of different N-fertilizer treatments (0 (N0), 220 (N20), 440 (N40), 660 (N60) and 880 (N80) kg N ha−1 year−1) on grazed pastures and to calculate the carbon footprint (CF) of milk produced. Excessive N-fertilization (N60 and N80) did not increase herbage dry matter and energy yields from pastures. However, N80 indicated the highest N-yield but at the same time also the highest N surpluses at field level. A maximum fertilizer rate of 220 kg ha−1 year−1 (in addition to excreted N from grazing animals) appears sufficient to ensure adequate herbage yields (~20 t DM ha−1 year−1) with a slightly positive field-N-balance. This amount will prevent the depletion of soil C and N, with low N losses to the environment, where adequate milk yields of ~17 t ECM ha−1 with a low CF (~1.3 kg CO2 kg ECM−1) are reached. Methane from enteric fermentation (~49% ± 3.3) and N2O (~16% ± 3.2) emissions from irrigated pastures were the main contributors to the CF. A further CF reduction can be achieved by improved N-fertilization planning, low emission irrigation techniques and strategies to limit N2O emissions from pasture soils in South Africa.

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The nitrogen, carbon and greenhouse gas budget of a grazed, cut and fertilised temperate grassland

10.5194/bg-2016-221 ◽

2016 ◽

Cited By ~ 1

Author(s):

Stephanie K. Jones ◽

Carole Helfter ◽

Margaret Anderson ◽

Mhairi Coyle ◽

Claire Campbell ◽

...

Keyword(s):

Greenhouse Gas ◽

Soil Layer ◽

The Body ◽

Sink Strength ◽

N2o Emissions ◽

N Budget ◽

N Losses ◽

Enteric Fermentation ◽

C And N ◽

Ch4 And N2o

Abstract. Intensively managed grazed grasslands in temperate climates are globally important environments for the exchange of the greenhouse gases (GHGs) carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4). We assessed the N and C budget of a mostly grazed, occasionally cut, and fertilized grassland in SE Scotland by measuring or modelling all relevant imports and exports to the field as well as changes in soil C and N pools over time. The N budget was dominated by import from inorganic and organic fertilisers (21.9 g N m2 yr−1) and losses from leaching (5.3 g N m2 yr−1), N2 emissions and NOx and NH3 volatilisation (6.4 g N m2 yr−1). The efficiency of N use by animal products (meat and wool) averaged 11 %. On average over nine years (2002–2010) the balance of N fluxes suggested that 7.2 ± 4.6 g N m−2 y−1 (mean ± confidence interval at p > 0.95) were stored in the soil. The largest component of the C budget was the net ecosystem exchange of CO2 (NEE), at an average uptake rate of 218 ± 155 g C m−2 y−1 over the nine years. This sink strength was offset by carbon export from the field mainly as harvest (48.9 g C m2 yr−1) and leaching (16.4 g C m2 yr−1). The other export terms, CH4 emissions from the soil, manure applications and enteric fermentation were negligible and only contributed to 0.02–4.2 % of the total C losses. Only a small fraction of C was incorporated into the body of the grazing animals. Inclusion of these C losses in the budget resulted in a C sink strength of 163 ± 140 g C m−2 y−1. On the contrary, soil stock measurements taken in May 2004 and May 2011 indicated that the grassland sequestered N in the 0–60 cm soil layer at 4.51 ± 2.64 g N m−2 y−1 and lost C at a rate of 29.08 ± 38.19 g C m−2 y-1, respectively. Potential reasons for the discrepancy between these estimates are probably an underestimation of C and N losses, especially from leaching fluxes as well as from animal respiration. The average greenhouse gas (GHG) balance of the grassland was −366 ± 601 g CO2 eq m−2 y−1 and strongly affected by CH4 and N2O emissions. The GHG sink strength of the NEE was reduced by 54 % by CH4 and N2O emissions. Enteric fermentation from the ruminating sheep proved to be an important CH4 source, exceeding the contribution of N2O to the GHG budget in some years.

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Intensive Cultivation of Kiwifruit Alters the Detrital Foodweb and Accelerates Soil C and N Losses

Frontiers in Microbiology ◽

10.3389/fmicb.2019.00686 ◽

2019 ◽

Vol 10 ◽

Cited By ~ 2

Author(s):

María del Carmen F. Lago ◽

Pedro P. Gallego ◽

María J. I. Briones

Keyword(s):

N Losses ◽

Soil C ◽

Soil C And N ◽

C And N

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Autumn and spring applications of ammonium nitrate and urea to bromegrass influence total and light fraction organic C and N in a thin Black Chernozem

Canadian Journal of Soil Science ◽

10.4141/s00-084 ◽

2002 ◽

Vol 82 (2) ◽

pp. 211-217 ◽

Cited By ~ 5

Author(s):

S S Malhi ◽

J T Harapiak ◽

M. Nyborg ◽

K S Gill ◽

N A Flore

Keyword(s):

Ammonium Nitrate ◽

N Fertilization ◽

Light Fraction ◽

Total N ◽

Organic C ◽

Soil C ◽

Soil C And N ◽

C And N ◽

Light Fraction Organic C ◽

Total Organic C

An adequate level of organic matter is needed to sustain the productivity, improve the quality of soils and increase soil C. Grassland improvement is considered to be one of the best ways to achieve these goals. A field experiment, in which bromegrass (Bromus inermis Leyss) was grown for hay, was conducted from 1974 to 1996 on a thin Black Chernozemic soil near Crossfield, Alberta. Total organic C (TOC) and total N (TN), and light fraction organic C (LFOC) and light fraction N (LFN) of soil for the treatments receiving 23 annual applications of 112 kg N ha-1 as ammonium nitrate (AN) or urea in early autumn, late autumn, early spring or late spring were compared to zero-N check. Soil samples from 0- to 5- cm (layer 1), 5- to 10- cm (layer 2), 10- to 15- cm (layer 3) and 15- to 30-cm depths were taken in October 1996. Mass of TOC, TN, LFOC and LFN was calculated using equivalent mass technique. The concentration and mass of TOC and LFOC, TN and LFN in the soil were increased by N fertilization compared to the zero-N check. The majority of this increase in C and N occurred in the surface 5-cm depth and predominantly occurred in the light fraction material. In layer 1, the average increase from N fertilization was 3.1 Mg C ha-1 for TOC, 1.82 Mg C ha-1 for LFOC, 0.20 Mg N ha-1 for TN and 0.12 Mg N ha-1 for LFN. The LFOC and LFN were more responsive to N fertilization compared to the TOC and TN. Averaged across application times, more TOC, LFOC, TN and LFN were stored under AN than under urea in layer 1, by 1.50, 1.21, 0.06 and 0.08 Mg ha-1, respectively. Lower volatilization loss and higher plant uptake of surfaced-broadcast N were probable reasons from more soil C and N storage under AN source. Time of N application had no effect on the soil characteristics studied. In conclusion, most of the N-induced increase in soil C and N occurred in the 0- to 5-cm depth (layer 1) and in the light fraction material, with the increases being greater under AN than urea. Key words: Bromegrass, light fraction C and N, N source, soil, total organic C and N

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Straw export in continuous winter wheat and the ability of oil radish catch crops and early sowing of wheat to offset soil C and N losses: A simulation study

Agricultural Systems ◽

10.1016/j.agsy.2016.01.002 ◽

2016 ◽

Vol 143 ◽

pp. 195-202 ◽

Cited By ~ 5

Author(s):

C. Peltre ◽

M. Nielsen ◽

B.T. Christensen ◽

E.M. Hansen ◽

I.K. Thomsen ◽

...

Keyword(s):

Winter Wheat ◽

Simulation Study ◽

Catch Crops ◽

N Losses ◽

Soil C ◽

Soil C And N ◽

C And N

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Divergent effects of elevated CO2, N fertilization, and plant diversity on soil C and N dynamics in a grassland field experiment

Plant and Soil ◽

10.1007/s11104-004-3848-6 ◽

2005 ◽

Vol 272 (1-2) ◽

pp. 41-52 ◽

Cited By ~ 88

Author(s):

Feike A. Dijkstra ◽

Sarah E. Hobbie ◽

Peter B. Reich ◽

Johannes M. H. Knops

Keyword(s):

Field Experiment ◽

Elevated Co2 ◽

Plant Diversity ◽

N Fertilization ◽

N Dynamics ◽

Soil C ◽

Soil C And N ◽

C And N ◽

C And N Dynamics

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Reducing N Fertilization without Yield Penalties in Maize with a Commercially Available Seed Dressing

Agronomy ◽

10.3390/agronomy11030407 ◽

2021 ◽

Vol 11 (3) ◽

pp. 407 ◽

Cited By ~ 1

Author(s):

Stefania Codruta Maris ◽

Federico Capra ◽

Federico Ardenti ◽

Marcello E. Chiodini ◽

Roberta Boselli ◽

...

Keyword(s):

Grain Yield ◽

Root Length Density ◽

Maize Yield ◽

N Fertilization ◽

N2o Emissions ◽

Experimental Conditions ◽

N Losses ◽

Soil Microbial ◽

Seed Dressing ◽

Productivity Potential

Introducing smart and sustainable tools for climate change adaptation and mitigation is a major need to support agriculture’s productivity potential. We assessed the effects of the processed gypsum seed dressing SOP® COCUS MAIZE+ (SCM), combined with a gradient of N fertilization rates (i.e., 0%, 70% equal to 160 kg N ha−1, and 100% equal to 230 kg N ha−1) in maize (Zea mays L.), on: (i) grain yield, (ii) root length density (RLD) and diameter class length (DCL), (iii) biodiversity of soil bacteria and fungi, and (iv) Greenhouse Gases (GHGs, i.e., N2O, CO2, and CH4) emission. Grain yield increased with SCM by 1 Mg ha−1 (+8%). The same occurred for overall RLD (+12%) and DCL of very fine, fine, and medium root classes. At anthesis, soil microbial biodiversity was not affected by treatments, suggesting earlier plant-rhizosphere interactions. Soil GHGs showed that (i) the main driver of N losses as N2O is the N-fertilization level, and (ii) decreasing N-fertilization in maize from 100% to 70% decreased N2O emissions by 509 mg N-N2O m−2 y−1. Since maize grain yield under SCM with 70% N-fertilization was similar to that under Control with 100% N-fertilization, we concluded that under our experimental conditions SCM may be used for reducing N input (−30%) and N2O emissions (−23%), while contemporarily maintaining maize yield. Hence, SCM can be considered an available tool to improve agriculture’s alignment to the United Nation Sustainable Development Goals (UN SDGs) and to comply with Europe’s Farm to Fork strategy for reducing N-fertilizer inputs.

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INTERCROPPING AND N FERTILIZATION EFFECTS ON STRIGA INFESTATION, SOIL C AND N AND GRAIN YIELD OF MAIZE IN THE SOUTHERN GUINEA SAVANNA OF NIGERIA

Journal of Plant Development ◽

10.47743/jpd.2021.28.1.876 ◽

2021 ◽

pp. 97-108

Author(s):

Moses Samuel BASSEY ◽

Joy Ekaette ETOPOBONG ◽

Bigun Ishaku PONMAN ◽

Sheriff Adam BADOM ◽

Aliyu USMAN ◽

...

Keyword(s):

Grain Yield ◽

N Fertilization ◽

Soil C ◽

Guinea Savanna ◽

Soil C And N ◽

C And N ◽

Fertilization Effects

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Tracking the Deposition and Sources of Soil Carbon and Nitrogen in Highly Eroded Hilly-Gully Watershed in Northeastern China

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18062971 ◽

2021 ◽

Vol 18 (6) ◽

pp. 2971

Author(s):

Na Li ◽

Yanqing Zhang ◽

Zhanxiang Sun ◽

John Yang ◽

Enke Liu ◽

...

Keyword(s):

Organic Carbon ◽

Best Management Practices ◽

Management Practices ◽

Northeastern China ◽

Nutrient Loss ◽

N Loss ◽

N Losses ◽

Soil C ◽

Soil C And N ◽

C And N

Understanding the deposition and tracking the source of soil organic carbon (C) and nitrogen (N) within agricultural watersheds are critical for assessing soil C and N budgets and developing watershed-specific best management practices. Few studies have been conducted and reported on highly eroded hilly-gully watersheds. In this field study, a constructed dam-controlled hilly-gully watershed in northeastern China was selected to identify the sources of soil C and N losses. Soils at various land uses and landscape positions, and sediments near the constructed dam, were collected and analyzed for selected physiochemical properties, total organic carbon (TOC), total nitrogen (TN), and stable isotopes (13C and 15N). Soil C and N loss and deposition in the watershed were assessed and the relative contributions of each source quantified by a stable isotope mixing model (SIAR). Results indicated that soil C loss was primarily from cropland, accounting for 58.75%, followed by gully (25.49%), forest (9.2%), and grassland (6.49%). Soil N loss was similar to soil C, with cropland contribution of 80.58%, gully of 10.30%, grassland of 7.54%, and forest of 1.59%. The C and N deposition gradually decreased along the direction of the runoff pathway near the constructed dam, and the deposited C and N from cropland and gullies showed an order: middle-dam > bottom-dam > upper-dam and upper-dam > bottom-dam > middle-dam, respectively. A high correlation between soil TOC or TN and the sediment properties suggested that the deposition conditions could be the major factors affecting the C and N pools in the sedimentary zones. This study would provide a scientific insight to develop effective management practices for soil erosion and nutrient loss control in highly eroded agriculture watersheds.

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Very Low Nitrogen Leaching in Grazed Ley-Arable-Systems in Northwest Europe

Agronomy ◽

10.3390/agronomy11112155 ◽

2021 ◽

Vol 11 (11) ◽

pp. 2155

Author(s):

Hendrik P. J. Smit ◽

Thorsten Reinsch ◽

Christof Kluß ◽

Ralf Loges ◽

Friedhelm Taube

Keyword(s):

Nitrate Leaching ◽

C Sequestration ◽

Winter Precipitation ◽

Catch Crop ◽

Pasture Management ◽

N Losses ◽

Leaching Losses ◽

Soil C ◽

Permanent Grassland ◽

Northwest Europe

High input dairy farms that are located on sandy soils in northwest Europe are predisposed to substantial nitrate leaching during a surplus of winter precipitation. Leys within integrated crop-livestock systems play an important role in soil fertility, soil C sequestration and soil N mineralization potentials. Therefore, leys are a feasible option that can be utilized to reduce local N losses to the environment, especially following maize grown for silage. We hypothesize that grass-clover leys ensure low nitrate leaching losses even when grazed intensively. The extent to which NO3-leaching occurred across seven different pasture management systems in terms of their sward composition, cutting, grazing, fertilization and combinations thereof was investigated in integrated animal-crop grazing systems over three winter periods (2017/2018, 2018/2019 and 2019/2020). The observed grazed systems were comprised of cut-used- and grazed grass-clover swards (0, 1 and 2 years after establishment following cereals), a catch crop grazed late in the year as well as a cut-used permanent grassland for comparison. Overall, all treatments resulted in nitrate leaching losses that did not exceed the WHO-threshold (25 mg nitrate/L). The highest level of NO3-leaching was observed in the catch crop system and the lowest in cut-used permanent grassland, with NO3-N losses of 19.6 ± 5.3 and 2.1 ± 0.3 kg NO3-N ha−1 year−1. Annual herbage yields were in the range of 0.9 to 12.4 t DM ha−1 and nitrogen yields varied between 181 ± 51 and 228 ± 66 kg N ha−1 during the study period. The highest herbage-N-yields were observed from the 1- and 2-year-old grass-clover leys. The highest N-field-balance was observed for the grazed leys and the lowest for the cut-used permanent grassland. However, no correlation was found between the highly positive field-N-balance and the amount of NO3-leached. This indicates a high N carry-over from grass-clover swards to the subsequent cash crop unit instead of increasing the risk of groundwater contamination from grazed leys in integrated animal crop-systems and underlines the eco-efficiency of dairy farming based on grazed ley systems.

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Effects of fertilizer and biochar applications on the relationship among soil moisture, temperature, and N2O emissions in farmland

PeerJ ◽

10.7717/peerj.11674 ◽

2021 ◽

Vol 9 ◽

pp. e11674

Author(s):

Xiao Wang ◽

Ping Lu ◽

Peiling Yang ◽

Shumei Ren

Keyword(s):

Soil Moisture ◽

Soil Improvement ◽

Sensitivity Coefficient ◽

Exponential Model ◽

N2o Emissions ◽

Deep Soil ◽

Soil C ◽

Soil C And N ◽

C And N ◽

The Impact

Background Di-nitrogen oxide (N2O) emissions from soil may lead to nonpoint-source pollution in farmland. Improving the C and N content in the soil is an excellent strategy to reduce N2O emission and mitigate soil N loss. However, this method lacks a unified mathematical index or standard to evaluate its effect. Methods To quantify the impact of soil improvement (C and N) on N2O emissions, we conducted a 2-year field experiment using biochar as carbon source and fertilizer as nitrogen source, setting three treatments (fertilization (300 kg N ha−1), fertilization + biochar (30 t ha−1), control). Results Results indicate that after biochar application, the average soil water content above 20 cm increased by ∼26% and 26.92% in 2019, and ∼10% and 12.49% in 2020. The average soil temperature above 20 cm also increased by ∼2% and 3.41% in 2019. Fertigation significantly promotes the soil N2O emissions, and biochar application indeed inhibited the cumulation by approximately 52.4% in 2019 and 33.9% in 2020, respectively. N2O emissions strongly depend on the deep soil moisture and temperature (20–80 cm), in addition to the surface soil moisture and temperature (0–20 cm). Therefore, we established an exponential model between the soil moisture and N2O emissions based on theoretical analysis. We find that the N2O emissions exponentially increase with increasing soil moisture regardless of fertilization or biochar application. Furthermore, the coefficient a < 0 means that N2O emissions initially increase and then decrease. The aRU < aCK indicates that fertilization does promote the rate of N2O emissions, and the aBRU > aRU indicates that biochar application mitigates this rate induced by fertilization. This conclusion can be verified by the sensitivity coefficient (SCB of 1.02 and 14.74; SCU of 19.18 and 20.83). Thus, we believe the model can quantify the impact of soil C and N changes on N2O emissions. We can conclude that biochar does significantly reduce N2O emissions from farmland.

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