Search

• The rice (Oryza sativa)–rice system (RRS) is principal production system in Asia. • Loss of soil carbon and nitrogen pools is declining the productivity of RRS. • Intensive tillage and improper nutrient management are reasons of the loss of soil C and N. • RT/NT with INM and residue recycling can sequestrate C and N in paddy soils. • Cultivation RRS under CA with INM/IPNM and residue recycling could enhance productivity. The rice (Oryza sativa)–rice system (RRS) is the most important agricultural production system, and it provides staple food, income, employment, and livelihoods to millions of farmers in the Indian sub- continent, especially in the eastern and north eastern region (NER) of India. However, soil degradation, due to loss of soil carbon (C) and nitrogen (N) pools, is declining the productivity of RRS and threatening the region's food security. Intensive tillage along with improper residues and nutrient management practices are among the reasons of the loss of soil C and N pools and decline in rice productivity. Therefore, a 3-year (2013-15) field study was conducted to evaluate the effects of tillage, residues and nutrient management practices on productivity, soil C and N sequestration in RRS at the Indian Council of Agricultural Research (ICAR)-Research Complex for the North Eastern Hill (NEH) Region, Lembucherra (52 m, above sea level), Tripura, India. The experiment consisted of five combinations of tillage [conventional tillage (CT), reduced tillage (RT) and no-till (NT)], residue [30% rice residue incorporation (RI) and/or residue retention (RR)] and nutrient management practices [inorganic, organic (FYM-farmyard manure, GLM-green leaf manuring) and biofertilizers] in wet (WR) and dry season rice (DR). Results revealed that RT along with improved plant nutrient management (IPNM) comprising 25% N (20 kg N) through GLM + 60 kg N, 9 kg phosphorus (P), 17 kg potassium (K), 2 kg Boron (B) and 5 kg zinc (Zn) ha−1 through fertilizer + cellulose decomposition microorganism and RR in WR produced significantly higher grain yield (5.15 Mg ha−1) as compared to other treatments. However, the DR transplanted under CT + integrated nutrient management (INM) comprising 25% N through FYM and 75% N and remaining P and K (after deducting quantity supplied by FYM) through inorganic fertilizer + RI produced more grain (5.1–5.3 Mg ha−1), straw (7.0–7.2 Mg ha−1), root (1.3–1.4 Mg ha−1) and total biomass (13.4–13.9 Mg ha−1) yield than that of the farmers' practice (FP) and other treatment combinations, across the years. The highest system productivity of RRS was recorded under T 3 (RT + IPNM + RR in WR and CT + INM + RI in DR). Therefore, the highest biomass, C, and N were also recycled in the system through the same treatment combinations. Soil under T 3 had a lower bulk density (ρ b), the highest soil organic carbon (SOC)/N concentration, pool, accumulation, sequestration, C retention efficiency, soil microbial biomass C and dehydrogenase activities than other treatments. A total amount of 1.30 Mg C ha−1 was accumulated under soils of T 3 with the rate of SOC sequestration of 427.9 kg ha−1 yr−1 under RRS. Thus, adopting RRS under RT/NT with INM/IPNM and effective residue recycling is recommended for enhancing the system productivity, C and N sequestration in paddy soils of the NER of India. [ABSTRACT FROM AUTHOR]

Highlights • Sequestration of more carbon is the key for sustainable management of sloping lands. • No-till with residue retention (NT-RR) enhanced carbon sequestration and retention. • Inclusion of cowpea in a rice-rapeseed system doubled the carbon sequestration. • NT-RR can sequestrate ∼ 6.8–13.7 Mg C ha−1 in a period of 15–30 years in the region. • Restoration of the precious carbon has the potential to mitigate climate change. Abstract Decline in soil organic carbon (SOC) and low biomass production in sloping uplands are of growing concern for sustainable agriculture worldwide. This concern is in general in the Eastern Himalayan regions (EHR) of India in particular. A field experiment was conducted with the objectives to generate additional biomass and sequester more C in coarse-textured sloping lands. This experiment is done for four consecutive years in the EHR, India. The rice (Oryza sativa L.)–rapeseed (Brassica campestris L. var. rapeseed) cropping system was practiced during the first two years (2012-13 to 2013-14) and rice–rapeseed–cowpea (Vigna unguiculata L.) system during the two following years (2014-15 to 2015-16) of the study under different tillage and mulch systems. The tillage system included: 1) CT-RI: conventional tillage (CT) with 100% residue incorporation (RI) and 2) NT-RR: no-till (NT) with 100% residue retention (RR). The mulches included 1) rice straw mulch (SM), 2) Gliricidia sp. mulch (GM), 3) brown manuring mulch (BM)–cowpea grown as intercrop with rice up to 40 days after sowing (DAS), killed with 2,4-D and 4) no mulch (NM). The cowpea, as a cover crop was introduced during 2014 and 2015 as pre-rainy season crop before the sowing of rice to generate additional biomass in the system. The four year total above ground biomass yield of rice and rapeseed didn't vary significantly between CT-RI (31.93 and 17.40 Mg ha−1) and NT-RR (31.86 and 17.46 Mg ha−1), respectively. However, the total above ground biomass yield of cowpea was more under NT-RR (10.75 Mg ha−1) when compared to that under CT-RI (9.79 Mg ha−1). The amount of total biomass (above + below ground) and C added into the soil was more under NT-RR than that under the CT-RI. After 4 cropping cycles, the NT-RR had higher SOC concentration, pool (29.9 vs. 29.1 Mg ha−1), sequestration rate (450 vs. 265 kg ha-1 yr−1) and C retention efficiency (7.7 vs. 4.6%) than those under the CT-RI at 0–30 cm depth. The mulched plots produced more crop biomass (both above and below ground), recycled more C in soils with a trend of relatively more SOC pool (29.7–29.8 vs. 29.0 Mg ha−1), sequestration rate (391–428 vs. 221 kg ha-1 yr−1) and C retention efficiency (6.64–6.94% vs. 4.66%) than those of NM treatment. These results were seen despite difference among the mulch treatments (SM, GM and BM) which were statistically non-significant after 4 cropping cycles. Inclusion of cowpea as cover crop during pre-rainy season in the system doubled the rate of C sequestration (478 kg C ha-1 yr−1). Therefore, the data supports the recommendation of cultivation of the rice–rapeseed system under NT-RR along with cowpea intercropping up to 40 DAS (BM) in rice. Besides this, the inclusion of pre-rainy season cowpea before rice could generate additional biomass and enhance SOC sequestration on upland and sloping hills in the EHR of India and in similar conditions elsewhere. [ABSTRACT FROM AUTHOR]

Research information from a systematic planned study on the effects of vehicular passages and axle load on soil carbon dioxide (CO2) fluxes and soil carbon (C) sequestration under long‐term NT farming is scanty. Therefore, the present study was conducted on an on‐going 20‐year experiment to assess the impacts of variable vehicular passages of a low axle load on soil CO2 emission and soil C sequestration from a no‐till (NT) managed corn (Zea mays L.)–soybean (Glycine max Linneo) rotation in comparison with that a soil under woodlots (soils under natural wooded plantation). The experimental treatment consisted of an empty wagon [0 Mg load for compaction (C‐0; control)] compared with 2 (C‐2) and 4 (C‐4) passages of 2.5 Mg water wagon axle load, applied to the entire plot every year during April/May for 20 consecutive years. Soil samples were obtained in November 2016 to determine the effects of various vehicular passages on C and nitrogen (N) contents and CO2 emissions. Soil CO2 fluxes were measured from November 16, 2016, to May 30, 2017, on the bi‐weekly (November to December and April to May) and monthly (January to March) basis by using high‐density polyvinyl chloride static gas chambers. The soil CO2 fluxes ranged from –1.05 to 9.03 g CO2 m−2 d−1. The lowest soil CO2 fluxes were observed in December coinciding with the minimum soil temperature. In general, daily soil CO2 fluxes were higher under C‐0 than those under other treatments. Vehicular traffic and axle load reduced the cumulative emission of CO2 by 22.6 and 29.8% under C‐2 and C‐4, respectively, compared with that under C‐0 (6.09 Mg ha−1). Soil and air temperatures had a significant positive correlation with the diurnal fluxes of soil CO2 in all the treatments except that under C‐4. Electrical conductivity, soil C and N contents and pools did not differ significantly among the treatments. Further, 2 to 4 passages of vehicles with 2.5 Mg of axle load decreased the soil CO2 emission on Crosby silt loam under NT as compared to that under the control. Therefore, continuous cultivation of row crops with moderate trafficking under NT and residue retention is recommended, and it also reduces the potential of soil CO2 emission while improving the soil organic C pools of well‐drained soils of Central Ohio. [ABSTRACT FROM AUTHOR]

Amid the current environmental crises that exert enormous pressure on the arable lands, there is a need to adopt environment-friendly effective but highly productive conservation agriculture practices to feed the growing world population. Thus, a study was conducted to test the hypothesis that the inclusion of cowpea (Vigna unguiculata L. Walp) live mulch under no-till and reduced tillage in the summer maize (Zea mays L.) – rainy season maize-mustard (Brassica juncea (L.) czern) sequence would enhance agronomic productivity, energy use efficiency, and water productivity while reducing greenhouse gases emissions. Five tillage treatments viz., no-till, no-till-live mulch, reduce tillage, reduce tillage-live mulch, and conventional tillage were evaluated in three times replicated randomized complete block design. Land productivity for maize–maize–mustard system was the highest under reduced tillage-live mulch. No-till-live mulch had 36.4% lesser energy requirement, 2.4 times more energy productivity than that under conventional tillage. Reduced tillage-live mulch and no-till-live mulch had higher water productivity compared to all other treatments. The conventional tillage had the highest net CO 2 -eq emission while no-till-live mulch had the lowest. Inclusion of cowpea as live mulch enhanced C sequestration which has the potential to offset approximately half of the total CO 2 emission, enhance energy use efficiency, land and water productivity. The findings of this study might be useful to develop a policy for sustainable high productivity through efficient resource use in the Eastern Himalayan Ecosystems that have the potential to become the corn belts of India. • Inclusion of cowpea live mulch under no-till (NT-LM) and reduced tillage (RT-LM) increased crop and land productivity. • The NT-LM/RT-LM increased energy use efficiency and crop productivity. • The NT-LM/RT-LM increased water productivity and decreased water footprint. • The NT-LM/RT-LM increased carbon sequestration and decreased carbon footprint. • The NT-LM/RT-LM decreased the cost of production and increased net profit. [ABSTRACT FROM AUTHOR]

• The impact of 20-yr of using amendments on soil properties of an Alfisol. • The magnitude and rate of SOC accretion were 27.5 Mg C/ha and 2.0 Mg/ha.yr. • The highest rate of build-up of C and N stocks was recorded in compost-amended plots. • Fertilizers are not sufficient to restore SOC stocks in the eroded soils. The impacts of 20-yr using amendments on the restoration of properties of an Alfisol was evaluated at the Waterman Farm, Agricultural and Natural Resources Laboratory, Columbus, Ohio. The objectives of the experiment were to assess: (1) the effects of organic and inorganic amendments on soil aggregates, and (2) carbon (C) and nitrogen (N) budgets of soil removed (20 cm deep) and undisturbed plots after 20-yr was used to conduct the experiment. Five treatmentents were used in the rendomized block design viz; (1) permanent grass field, (2) soil artificially removed-N fertilizer added, (3) soil artificially removed-compost added, (4) an undisturbed (surface soil not removed)-N fertilizer added, and (5) an undisturbed surface soil-compost added. The experiment field was permanently under the no-till since last 20 yr. The surface soil removal plots amended with compost and permanent grass plots registered the lowest bulk density (ρ b) of 1.37 and 1.38 Mg/m3, respectively. The highest concentration of sand (30.4%) was observed in the treatment with surface soil removed and compost added, while the highest silt content (48.0%) was obtained in permanent grass plots. However, the clay content was the highest (38.2%) in fertilizer amended undisturbed treatment. The higher proportion of macroaggregates (88.0 and 87.6%) and the mean weight diameter (MWD) (4.47 and 4.5 mm) were recorded in the undisturbed compost-amended and permanent grass plots, respectively compare to fertilizer applied plots. There were no differences in soil pH among sampling depths, but higher electrical conductivity (EC) was observed at 0–10 cm depth of fertilizer application, disturbed (174.23 µS/cm) and undisturbed (166.63 µS/cm) plots than 10–20 cm. The highest C:N ratio (11.0) was observed at the of 0–10 cm depth in artificaly soil removed organic compost-amended treatments. The highest rate of build-up of stocks was 793.3 Kg/ha for C and 50.5 kg/ha for N in 0–10 cm depth of undisturbed and compost-amended plots. Furthermore, the highest magnitude of the stabilization was 2.8 Mg/ha for C and 0.7 Mg/ha for N in surface soil removed and compost-amended treatment. The magnitude and rate of SOC accretion were 27.5 Mg C/ha and 2.0 Mg/ha.yr, respectively, under undisturbed and compost-amended treatment. [ABSTRACT FROM AUTHOR]

• Different rice-based sequences have been tested under organic farming. • Inclusion of legumes increased rice grain yield under organic farming. • Rice-broccoli-sesbania sequence had the highest very labile carbon and CMI. • The addition of the third crop increased the active carbon pool in 0–40 cm depth. The contribution of soil to supporting, regulating, provisioning and cultural functions as well as its role in the ecosystem services is well-known in the international literature. However, in the domain of organic agriculture, the impact of cropping systems shifts from cereal-cereal to high-frequency diversified cropping sequences with legume as a component crop on soil carbon dynamics is not widely known. In order to identify an alternative cropping system to widely prevalent rice-fallow production system in Himalayan region of India, seven cropping sequences viz. , rice -fenugreek (green vegetable) - maize (R-F-M); rice -vegetable pea - maize (R-Vp-M); rice-coriander (leaves)-cowpea (R-C-Cp); rice - fenugreek (green vegetable) - baby corn (R-F-Bc); rice - broccoli - Sesbania (green manuring) (R-B-S); rice - buckwheat (R-Bw) and rice - maize (R-M) were assessed for five consecutive years from 2013 to 2018 for their productivity and resource conservation values. Results revealed that the inclusion of legumes in rice-based sequences increased the rice grain yield by 13.4 to 24.6% over R-M (3.13 Mg ha−1) sequence. The R-B-S sequence had the highest very labile carbon (VLC) (4.6 g kg−1 soil) followed by the R-Vp-M. Relative proportion of various organic carbon fractions in the top 10 cm soil followed the order of VLC (30.2%) > non labile carbon (NLC, 27.6%) > labile carbon (LC, 23.4%) > less labile carbon (LLC, 18.9%). The carbon management index (CMI) was the highest (100.9%) in the R-B-S sequence followed by R-C-Cp (98.0%). The addition of a third crop in the sequence increased the active carbon (AC) pool by 1.1 to 5.8%. The passive carbon (PC) pool was highest in soil under the R-C-Cp sequence (9.15 Mg ha−1) at 0–10 cm soil depth. The carbon retention efficiency under the R-C-Cp cropping sequence was the highest (15.1%) followed by the R-B-S (14.9%). R-B-S and R-C-Cp sequences had 12.5% and 10.6% higher soil microbial biomass carbon (SMBC) over the R-M sequence, respectively. Similarly, R-B-S and R-C-Cp increased the FDA by 49.6 and 41.8%, and DHA by 135.0% and 103.9%, respectively over R-M sequence. In conclusion, the management of crops from organic agriculture aimed at improving soil ecosystem services, in contrasting degradation of soil health and the decline of SOC, can also have positive effects on crop productivity in the eastern Himalayan region of India as well as all over the world. [ABSTRACT FROM AUTHOR]