Search

Purpose: Improving agricultural carbon-output efficiency is an important path to realize the "double carbon" goal in the Yellow River Basin. In the context of rapid urbanization development, it is significant to explore whether promoting urbanization will affect agricultural carbon-output efficiency. Methods: Based on panel data of 75 cities in the Yellow River Basin from 2000 to 2020, this paper uses the super-DEA model, three-dimensional kernel density model, and Markov chain model to measure and analyze the spatio-temporal evolution of agricultural carbon-output efficiency in the Yellow River Basin. The panel Tobit model is used on this basis to analyze the relationship between urbanization and carbon-output efficiency in agriculture. Results: The results show the following: (1) The level of agricultural carbon-output efficiency in the Yellow River Basin is low and has not reached an effective state, showing a slow downward trend in general where the agricultural carbon-output efficiency in the lower reaches is higher than that in the middle reaches, and the upper reaches has the lowest. (2) Agricultural carbon-output efficiency in the Yellow River Basin has a negative trend of transitioning to a low level overall and maintaining its original level, and it is difficult to realize the leapfrog transfer between states. Agricultural carbon-output efficiency has an obvious spatial spillover effect and "club convergence" phenomenon; the high-efficiency area has a positive driving effect on the neighborhood area, while the low-efficiency area has a negative impact on the neighborhood area. (3) The level of urbanization has a significant positive impact on the carbon-output efficiency of agriculture in the upper, middle, and lower reaches of the Yellow River Basin, which plays an important role in promoting the green development of agriculture. [ABSTRACT FROM AUTHOR]

Purpose: Improving agricultural carbon-output efficiency is an important path to realize the “double carbon” goal in the Yellow River Basin. In the context of rapid urbanization development, it is significant to explore whether promoting urbanization will affect agricultural carbon-output efficiency. Methods: Based on panel data of 75 cities in the Yellow River Basin from 2000 to 2020, this paper uses the super-DEA model, three-dimensional kernel density model, and Markov chain model to measure and analyze the spatio-temporal evolution of agricultural carbon-output efficiency in the Yellow River Basin. The panel Tobit model is used on this basis to analyze the relationship between urbanization and carbon-output efficiency in agriculture. Results: The results show the following: (1) The level of agricultural carbon-output efficiency in the Yellow River Basin is low and has not reached an effective state, showing a slow downward trend in general where the agricultural carbon-output efficiency in the lower reaches is higher than that in the middle reaches, and the upper reaches has the lowest. (2) Agricultural carbon-output efficiency in the Yellow River Basin has a negative trend of transitioning to a low level overall and maintaining its original level, and it is difficult to realize the leapfrog transfer between states. Agricultural carbon-output efficiency has an obvious spatial spillover effect and “club convergence” phenomenon; the high-efficiency area has a positive driving effect on the neighborhood area, while the low-efficiency area has a negative impact on the neighborhood area. (3) The level of urbanization has a significant positive impact on the carbon-output efficiency of agriculture in the upper, middle, and lower reaches of the Yellow River Basin, which plays an important role in promoting the green development of agriculture.

Crop residue or biomass is generally removed from the field as animal feed and fuel in many Asian countries. The impact of this practice on sustaining soil annual net carbon balance (ANCB) has not received much attention for cover crop-rice cropping systems in paddy soil. The influence of cover crop cultivation and biomass incorporation rates on ANCB needs to be evaluated in a rice-based cropping system. Above-ground biomass was harvested and incorporated at 3.0, 6.0 and 12.0 Mg ha−1 (dry weight) 1 week before rice transplanting and carbon (C) inputs and losses were compared with a control treatment i.e. 0 Mg biomass ha−1. The annual net C inputs and outputs significantly increased with the increased biomass incorporation rates. Applied organic C was lost mainly as CO2-C during cover crop cultivation, and as CH4-C and CO2-C during the rice growing season. About 81–90% of total organic C output was lost as CO2-C and 10–19% as CH4-C during the rice growing season. The net ecosystem C balance was negative (− 1402 to − 1523 kg C ha−1) with cover crop cultivation, but it was mostly positive (1071–2652 kg C ha−1) in the rice growing season depending on biomass incorporation rates. About 5.2 Mg ha−1 (43% of total harvest) cover crop biomass needs to be recycled for sustaining soil organic C stocks in paddy field. [ABSTRACT FROM AUTHOR]

Performance of eight rice (Oryza sativa L.) genotypes (IR 83383–B–B–129–4, IR 83387–B–B–27–4, IR88867– 9–1–1–4, IR88964–24–2–1–4, IR88964–11–2–2–4, IR88966–39–1–4–4, Rajendra Sweta and Rajendra Bhagwati) were evaluated in different levels of nitrogen (N) application, i.e. control, 50% RDN (60 kg N/ha), 100% RDN (120 kg N/ha) and 150% RDN (180 kg N/ha) during the rainy season of 2016–17 in lowland transplanted condition of Patna, Bihar. Significantly higher grain yields (5.19 t/ha) and net returns (` 52260/ha) were recorded with application of 180 kg N/ha. Grain yields and net returns were noted higher with IR 83383–B–B–129–4 (4.27 t/ha and ` 38181/ ha). Carbohydrate equivalent yield (4.06 t/ha) and carbon output (6.42 t CE/ha) were also higher with 150% RDN. IR83383–B–B–129–4 had significantly higher carbohydrate equivalent yield (3.34 t/ha) and carbon output (5.23 t CE/ ha). Gross energy output, net energy return, energy use efficiency, energy profitability, energy productivity, energy intensity in economic terms and energy output efficiency were markedly higher with 180 kg N/ha. These attributes were higher with IR83383–B–B–129–4 but being on a par with IR83387–B–B–27–4. Therefore, growing of IR 83383–B–B–129–4 along with application of 180 kg N/ha is an ideal approach to achieve the higher productivity, profitability and energetics in lowland transplanted condition of Bihar.

In the present investigation, we investigated the effects of staggered sowing and nutrition levels on productivity, profitability, quality and nutrient uptake of heat tolerant wheat (Triticum aestivum L.) cultivars during rabi season of 2014-16 at the Breeder Seed Production Unit, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, Madhya Pradesh. Soil of the experimental plot was clay in texture, medium in organic carbon and available NPK with neutral pH (7.4). Experiment was laid out in split-plot design with three replications. The main plots consisted of three staggered sowing, i.e. 30th November, 20th December and 10th January and three nutrition levels, viz. RDF (120:60:40 kg NPK/ha), 20% higher RDF and 20% lesser RDF, while three heat tolerant varieties, viz. MP 1203, MP 3336 and GW 173 were allotted in sub-plot. Results revealed that among the sowing time, grain yield (4.20 t/ha), straw yield (5.04 t/ha), biological yield (9.25 t/ha) and harvest index (45.3%) had recorded significantly higher in 30th November sowing. Crop sown on 30th November had increased the grain yield by 11.7 and 37.7% over that of 20th December and 10th January sowing, respectively. Among the nutrition levels, 20% higher RDF had recorded significantly higher grain yield (4.01 t/ha), straw yield (4.84 t/ha), biological yield (7.78 t/ha) and harvest index (45.1%) compared to RDF and 20% lesser RDF. Application of 20% higher RDF increased the grain yield to the tunes of 9.8 and 19.7% compared to RDF and 20% lesser RDF, respectively. Significantly higher grain yield was recorded with MP 3336 (4.05 t/ha) compared to MP1203 (3.59 t/ha) and GW173 (3.36 t/ha). Crop sown on 30th November had significantly higher gross returns (` 79218/ ha), net returns (` 55873/ha) and B:C ratio (3.39), respectively. Application of 20% higher RDF had maximum gross returns (` 75684/ha), net returns (` 51360/ha) and B: C ratio (3.11), respectively. MP 3336 had higher gross returns (` 76634/ha), net returns (` 53289/ha) and B: C ratio (3.28). Sowing on 30th November had significant superiority in nutrient content (NPK) in grain and straw as well as their uptake by crop. These attributes had significantly higher with application of 20% higher RDF. MP 3336 had higher NPK contents in grain and straw than that to MP 1203 and GW-173. Protein content had higher in 30th November sowing (16.01%). Application of 20% higher RDF had better protein content (15.43%). MP 3336 had markedly higher protein content (15.63%). Carbohydrate equivalent and carbon output had higher when crop sown on 30th November (3.0 and 4.1 /ha) along with 20% higher RDF (2.9 and 3.7 t/ha) in MP 3336 (2.9 and 4.0 t/ha), respectively. Therefore, sowing of heat tolerant wheat cv. MP 3336 on 30th November along with application of 20% higher RDF were proved the most ideal approach to achieve the higher productivity, profitability and nutrient uptake under the irrigated ecosystem of Madhya Pradesh.

Grassland degradation reduces net primary production and, subsequently, soil fertility and soil organic carbon stocks (SOCs); however, little is known about its impact on soil CO 2 emissions, particularly the emissions relative to SOCs and biomass produced. The main objective of this study, performed in KwaZulu-Natal province of South Africa, was to quantify the impact of grass basal cover, as main indicator of grassland degradation, on soil CO 2 emissions. The soil CO 2 emissions were measured from three grass cover levels (non-degraded, with 100% grass cover; moderately degraded: 25 < grass cover < 50%; and highly degraded: 0 < grass cover < 5%) using a LI-COR 6400XT. The measurements were done at three randomly selected positions in each grass cover level, from January 2013 to April 2015. At each position, measurements were done once during winter months and twice during summer months, resulting in a total of 1053 measurements for the entire study period. The measured average gross soil CO 2 emission was significantly higher (1.78 ± 0.013 g CO 2 -C m −2  day −1 ) in non-degraded than moderately (1.60 ± 0.12 g CO 2 -C m −2  day −1 ) and highly degraded grasslands (0.68 ± 0.10 g CO 2 -C m −2  day −1 ). However, when expressed relative to SOCs and aboveground biomass produced, the trends were opposite. Average soil CO 2 emission relative to SOCs was lowest in the non-degraded grassland (0.034 ± 0.01 g CO 2 -C g −1 C day −1 ) and highest in the moderately degraded grassland (0.058 ± 0.02 g CO 2 -C g −1 C day −1 ) with the highly degraded grassland being intermediate (0.04 ± 0.00 g CO 2  g −1 C day −1 ). Similarly, soil CO 2 emission relative to aboveground biomass produced was lowest in the non-degraded grassland at 0.15 ± 0.02 kg CO 2 -C kg −1  biomass year −1 , which was almost 5 fold lower than 0.73 ± 0.01 kg CO 2 -C kg −1  biomass year −1 in the highly degraded grassland. Gross soil CO 2 emission correlated significantly and positively with SOC (r = 0.83 and 0.82 for SOC content and stocks, respectively), SON (0.67 and 0.53 for content and stocks, respectively), C:N ration (0.62), and soil water content (0.75) but negatively with clay content (−0.89). Soil CO 2 emission relative to SOCs correlated significantly and negatively with both SOC (−0.50 and −0.51 for content and stocks, respectively) and SON (−0.45 and −0.42 for content and stocks, respectively). While gross CO 2 emissions decreased with grassland degradation, CO 2 emission relative to both SOCs and aboveground biomass increased with grassland degradation. These results point to direct links between grassland degradation and global warming because CO 2 is one of the key greenhouse gases. Therefore, strategies for rehabilitating degraded grasslands need to aim at reducing soil CO 2 emission in order to mitigate climate change. [ABSTRACT FROM AUTHOR]

Due to increased contribution from agriculture sector to total greenhouse gas emissions, there is need to study the ability of no-tilled diverse cropping systems including crop sequences and bio-covers to mitigate C equivalent emissions. Thus, C-footprint was calculated for a long-term experiment at the University of Tennessee's Research and Education Center in Milan with six-crop sequences: continuous cotton (Gossypium hirsutum L.), cotton-corn (Zea mays L.), continuous corn, corn-soybean (Glycine max L.), continuous soybean, and soybean-cotton interacted with four bio-covers: poultry litter, hairy vetch (Vicia villosa), winter wheat (Triticum aestivum), and fallow control with three replicates in a strip-plot design. During the experiment duration (2002–2017), field inputs (fertilizers, pesticides, and machinery used for planting, chemical applications, and harvesting) and outputs (crop yield, aboveground, and belowground residue) were assessed for each crop sequence/bio-cover combination to calculate total C equivalence of inputs and outputs, net C gain, C footprint per kg yield, sustainability index, and nitrous oxide emissions. For continuous corn, C-based input emissions were significantly higher by 0.28–0.62 Mg CO 2 eq. ha−1 yr−1 than all other sequences, however, a greater net C gain (5.4 Mg C eq. ha−1 yr−1) was also observed due to increased crop yield, aboveground and belowground residues. Poultry litter application resulted in lower C-footprint (1.59–2.09 kg CO 2 eq. kg−1 yield) than hairy vetch, wheat, and fallow under all crop sequences. Hairy vetch also lowered C-footprint per kg yield (∼2–14%) when compared with wheat under continuous systems of corn, soybean, and cotton, and cotton-corn rotation. Poultry litter application increased sustainability index (23–45) of all cropping sequences compared with other bio-covers. Hairy vetch improved sustainability index of corn including cropping sequences as compared with wheat and fallow. Inclusion of soybean and cotton with corn significantly decreased nitrous oxide emissions by 20–25%. The major factor contributing towards C-based input emissions was N fertilizer with 68% contribution to total emissions on average. It is concluded that application of poultry litter can reduce per yield C-footprint and enhance production system sustainability compared with hairy vetch, wheat, and fallow for monocultures or rotations of corn, soybean, cotton. Additionally, hairy vetch can outperform wheat in reducing the per yield C-footprint for continuous corn/soybean/cotton, and cotton-corn rotation. Especially for corn production systems, hairy vetch can enhance sustainability index compared with wheat and fallow. In order to increase per hectare net C gain, reduce per yield C-footprint and enhance sustainability index simultaneously, integration of continuous corn or corn-soybean/cotton rotation with bio-cover poultry litter or hairy vetch may perform better than the monocultures of soybean or cotton integrated with bio-cover wheat or fallow control in the Mid-south USA. • N fertilizer accounted for 68% of the total CO 2 equivalent emissions. • Poultry litter reduced C-footprint than bio-covers hairy vetch, wheat, and fallow. • Corn when rotated with soybean/cotton reduced nitrous-oxide emissions by 20–25%. • Continuous corn had highest net C gain compared with corn/soybean/cotton sequences. • Continuous soybean/cotton or rotation had lowest C-equivalent emissions than corn. [ABSTRACT FROM AUTHOR]

The agriculture sector, which accounts for about 52% of the total workforce despite a steady decline of its share in the gross domestic product (GDP), is still the largest economic sector that plays a significant role in the overall socio-economic development of India. Sustainability of agricultural production systems depends on their carbon (C) footprint and the C output-input ratio. Thus, the present study was conducted with the objectives to: (i) assess C emissions in relation to predominant agricultural systems in India; (ii) evaluate C-use efficiency of production systems; and (iii) determine the relative sustainability of agronomic production systems as determined by their C footprints. The data collated on C-based input into the soil for predominant agricultural and horticultural crops included the amounts of fertilizers (N, P, K), herbicides, and pesticides used for crops annually, cropland area, total production of each crop, water-management practices, energy used for different operations, and total number of livestock. These data were used to compute C equivalent (Ce) per hectare of input and output, and the relative sustainability indices as a measure of the C-production efficiency. Beginning with low C-based input of 69.7 Tg Ce/yr (1 Tg = teragram = 1012g = 1 million ton) in 1960-61, input of fertilizers, pesticides, farm power, feed, fodder, and electricity increased to 281.2 Tg Ce/yr by 2008-09. The output in agriculture increased from 578.6 Tg Ce/yr in 1960-61 to 1239.1 Tg Ce/yr in 2008-09. The C-sustainability index was high in 1960, and was indicative of the minimum usage of inputs prior to the onset of the Green Revolution. Thereafter, the C-sustainability index decreased during 1970s and 1980s because of increased C-based inputs. There existed a linear relationship between C input and C output, indicating that an increase of 1 Tg Ce/yr of C input resulted in a corresponding increase in C output of ∼21 Tg Ce/yr. Total food grain production in India increased from 89 million ton in 1960-61 to 262 million ton in 2008-09. [ABSTRACT FROM AUTHOR]

The Azores archipelago (Portugal) contains 88 lakes, two located inside caves spread across six of the nine volcanic islands of the archipelago; the formation of the lakes is associated with various types of volcanic structures. Surveys were performed on 45 water bodies corresponding to a representative data set and omitting only small ephemeral ponds to extensively research CO 2 emissions from the volcanic lakes. The modified accumulation chamber method was used to measure the CO 2 flux at the surface of the lakes; 16,119 measurements were performed with flux values ranging from 0 to 20,960 g m−2 d−1. Graphical statistical approaches identified different geochemical populations from the CO 2 flux data. Multiple populations associated with limnological and biogenic processes or volcanic/hydrothermal sources were identified in some cases. The influence of these sources was also confirmed by the determined δ13C content of the lakes. The lakes of the Azores emit approximately ~171 × 103 t yr−1 of CO 2 into the atmosphere; much of this is released by the Furnas and Furna do Enxofre lakes, both showing mantle-derived CO 2 origin. Deep-seated CO 2 accounts for approximately 42% of the total degassing. • Lake stratification influences the amount of CO 2 emitted to the atmosphere. • Higher CO 2 values are associated with lakes having CO 2 of volcanic origin. • Low CO 2 flux and δ13C content on lakes suggest biogenic CO 2 origin. • Total CO 2 degassing from Azores lakes to the atmosphere was estimated at ~171 × 103 t yr−1. • Total deep-seated CO 2 degassing was estimated at ~72 × 103 t yr−1. [ABSTRACT FROM AUTHOR]