• Authors:
    • Nieder, R.
    • Ma, W. Q.
    • Roelcke, M.
    • Heimann, L.
    • Gao, Z. L.
    • Hou, Y.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 92
  • Issue: 3
  • Year: 2012
  • Summary: An in-depth understanding of nutrient management variability on the regional scale is urgently required due to rapid changes in cropping patterns and farmers' resource use in peri-urban areas of China. The soil surface nitrogen (N) balances of cereal, orchard and vegetable systems were studied over a 2-year period on smallholder fields in a representative peri-urban area of Beijing. Positive soil surface N balances were obtained across all three cropping systems. The mean annual N surplus of the vegetable system was 1,575 kg N ha(-1) year(-1), or approximately 3 times the corresponding values in the cereal (531 kg N ha(-1) year(-1)) and orchard systems (519 kg N ha(-1) year(-1)). In the vegetable system, animal manure (1,443 kg N ha(-1) year(-1) on average) was the major source of N input (65 % of the total N input) and the factor with strongest impact on the N surplus. In the cereal system, however, about 74 % of the total N input originated from mineral fertilizer application which was the major contributor to the N surplus, while in the orchard system, the N surplus was strongly and positively correlated with both mineral fertilizer and animal manure applications. Furthermore, within each cropping system, N fertilization, crop yields and N balances showed large variations among different smallholder fields, especially in orchard and vegetable systems. This study highlights that differences in farming practices within or among cropping systems should be taken into account when calculating nutrient balances and designing strategies of integrated nutrient management on a regional scale.
  • Authors:
    • Yagi, K.
    • Xu, H.
    • Ma, J.
    • Liu, G.
    • Ji, Y.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 94
  • Issue: 1
  • Year: 2012
  • Summary: A 2-year field experiment was conducted to study effects of application rate of controlled-release fertilizer (CRF) and urea on N2O emission from a wheat cropping system. Two kinds of N fertilizers, CRF and urea, and four application rates (0, 100, 200 and 270 kg N ha(-1)) were used. Results indicate that the application of either urea or CRF, increased total N2O emission during the wheat growing period linearly from 32 to 164 %, with increasing N rate (p < 0.05), compared to the zero N control, and the increase was less significant in CRF than urea treatments. Compared with urea, CRF significantly reduced N2O emission by 25-56 % during the wheat growing period (p < 0.05), and the effect was more significant when N rate was higher. Grain yield increased in a power pattern from 24 to 43 % in urea treatments and from 30 to 45 % in CRF treatments with increasing N rate (p < 0.05). Specific N2O emission (N2O emission per unit of yield) increased linearly from 31 to 114 % in urea treatments (p < 0.05), and from 2 to 50 % in CRF treatments (p < 0.05), with increasing N rate. Compared with urea, CRF significantly inhibited specific N2O emission (p < 0.05), and the effect increased with increasing N rate. Peaks of N2O emission did not occur immediately after fertilization, but did immediately after rainfall events. CRF released fertilizer-N slowly, prolonging nitrogen supply and reducing peaks of N2O fluxes stimulated by rainfall. The application rate of CRF could be reduced by 26-50 % lower than that of urea for mitigating N2O emission without sacrificing grain yield. We would not risk any significant loss of wheat yield while achieving economic and environmental benefits by reducing urea or CRF application rate from 270 kg to 200 kg N ha(-1).
  • Authors:
    • Kuzyakov, Y.
    • Lal, R.
    • Yang, H. F.
    • Fan, M. S.
    • Gong, Y. S.
    • Chen, H. Q.
    • Liang, Q.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 92
  • Issue: 1
  • Year: 2012
  • Summary: Soil organic carbon (SOC) and its labile fractions are strong determinants of chemical, physical, and biological properties, and soil quality. Thus, a 15-year experiment was established to assess how diverse soil fertility management treatments for winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) cropping system affect SOC and total N (TN) concentrations in the North China Plain. The field experiment included three treatments: (1) unfertilized control (CK); (2) inorganic fertilizers (INF); and (3) farmyard manure (FYM). Concentrations of SOC, TN, and different labile SOC fractions were evaluated to 1-m depth. In comparison with INF and CK, FYM significantly increased SOC and TN concentrations in the 0-30 cm depth, and also those of dissolved organic C (DOC), microbial biomass C (MBC), hot-water extractable C (HWC), permanganate oxidizable C (KMnO(4)-C), and particulate organic C (POC) in the 0-20 cm depth. Despite the higher crop yields over CK, application of INF neither increased the SOC nor the labile C fractions, suggesting that by itself INF is not a significant factor affecting SOC sequestration. Yet, POC (18.0-45.8% of SOC) and HWC (2.0-2.8%) were the most sensitive fractions affected by applications of FYM. Significantly positive correlations were observed between SOC and labile organic C fractions in the 0-20 cm depth. The data support the conclusion that, wherever feasible and practical, application of FYM is important to soil C sequestration and improving soil quality under a wheat/maize system in the North China Plain.
  • Authors:
    • Wang, P. J.
    • Zhao, J. S.
    • Wu, J. S.
    • Ruan, L. L.
    • Hu, R. G.
    • Iqbal, J.
    • Lin, S.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 146
  • Issue: 1
  • Year: 2012
  • Summary: Red soil may play an important role in nitrous oxide (N 2O) emissions due to its recent land use change pattern. To predict the land use change effect on N 2O emissions, we examined the relationship between soil N 2O flux and environmental determinants in four different types of land uses in subtropical red soil. During two years of study (January 2005-January 2007), biweekly N 2O fluxes were measured from 09:00 to 11:00 a.m. using static closed chamber method. Objectives were to estimate the seasonal and annual N 2O flux differences from land use change and, reveal the controlling factors of soil N 2O emission by studying the relationship of dissolved organic carbon (DOC), microbial biomass carbon (MBC), water filled pore space (WFPS) and soil temperature with soil N 2O flux. Nitrous oxide fluxes were significantly higher in hot-humid season than in the cool-dry season. Significant differences in soil N 2O fluxes were observed among four land uses; 2.9, 1.9 and 1.7 times increased N 2O emissions were observed after conventional land use conversion from woodland to paddy, orchard and upland, respectively. The mean annual budgets of N 2O emission were 0.71-2.21 kg N 2O-N ha -1 year -1 from four land use types. The differences were partly attributed to increased fertilizer use in agriculture land uses. In all land uses, N 2O fluxes were positively related to soil temperature and DOC accounting for 22-48% and 30-46% of the seasonal N 2O flux variability, respectively. Nitrous oxide fluxes did significantly correlate with WFPS in orchard and upland only. Nitrous oxide fluxes responded positively to MBC in all land use types except orchard which had the lowest WFPS. We conclude that (1) land use conversion from woodland to agriculture land uses leads to increased soil N 2O fluxes, partly due increased fertilizer use, and (2) irrespective of land use, soil N 2O fluxes are under environmental controls, the main variables being soil temperature and DOC, both of which control the supply of nitrification and denitrification substrates.
  • Authors:
    • Lin, X. M.
    • Hubbard, K. G.
    • Yang, X. G.
    • Liu, Z. J.
  • Source: Global Change Biology
  • Volume: 18
  • Issue: 11
  • Year: 2012
  • Summary: Northeast China (NEC) is not only one of the major agricultural production areas in China, but it is also the most susceptible to climate variability. This led us to investigate the impact of climate change on maize potential yield and yield gaps in this region, where maize accounts for about 30% of the nation's production. The APSIM-Maize model was calibrated and validated for maize phenology and yields. The validated model was then used to estimate potential yields, rain-fed potential yields, and yield gaps for assessing the climate impacts on maize productivity in NEC. During maize growing seasons from 1981 to 2010, the analysis indicates a warming trend all across NEC, whereas the trends in solar radiation and total precipitation tended to decrease. When the same hybrid was specified in APSIM for all years, a simulated increase of maximum temperature resulted in a negative impact on both potential yield and rain-fed potential yield. A simulated increase in minimum temperature produced no significant changes in potential or rain-fed potential yield. However, the increase of minimum temperature was shown to result in a positive impact on the on-farm yield, consistent with our finding that farmers adopted longer season hybrids for which the increase in minimum temperature provided better conditions for germination, emergence, and grain filling during night time. The gap between potential and rain-fed potential yields was shown to be larger at locations with lower seasonal precipitation (<500 mm). Our results indicate that regions with the largest yield gaps between rain-fed potential and on-farm yields were located in the southeast of NEC. Within NEC, on-farm maize yields were, on average, only 51% of the potential yields, indicating a large exploitable yield gap, which provides an opportunity to significantly increase production by effective irrigation, fertilization, herbicide, and planting density in NEC.
  • Authors:
    • Zhang, F. S.
    • Yue, S. C.
    • Cui, Z. L.
    • Chen, X. P.
    • Sun, Q. P.
    • Meng, Q. F.
    • Romheld, V.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 146
  • Issue: 1
  • Year: 2012
  • Summary: Serious water deficits and excessive nitrogen (N) applications are threatening the sustainability of intensive agriculture in the North China Plain (NCP). This study examined the possibility of replacing the conventional system (Con.W/M) of winter wheat ( Triticum aestivum L.) and summer maize ( Zea mays L.), with an optimized double cropping system (Opt.W/M), a 2-year system (winter wheat/summer maize-spring maize, W/M-M), and a monoculture system (spring maize, M) based on optimal water and N management strategies. From 2004 to 2010, a long-term field experiment conducted in the NCP showed that although >70 mm of irrigation water can be saved with Opt.W/M compared with Con.W/M, annual net groundwater use under Opt.W/M was still 250 mm, 65-90% of which was consumed during the winter wheat season. When wheat production was decreased, 35% and 61% of irrigation water could be reduced in W/M-M and M compared to Con.W/M, respectively. As a result, annual groundwater use was decreased to 190 mm in W/M-M and 94 mm in M. Meanwhile, the N fertilizer rate was reduced 59% and 72% in W/M-M and M compared to Con.W/M, respectively. There were no significant differences in net economic returns between Con.W/M and W/M-M across the 6-year period. In the 6 years, no significant economic loss was observed between Con.W/M and M except in the 2008-2010 rotation. The W/M-M and M systems showed great potential to reduce water and N application and achieve groundwater use balance, and thus should be considered for economic and sustainable agricultural development in the NCP.
  • Authors:
    • Pan, S. F.
    • Huang, Y.
    • Tao, B.
    • Tian, H. Q.
    • Ren, W.
  • Source: Global Change Biology
  • Volume: 18
  • Issue: 9
  • Year: 2012
  • Summary: Much concern has been raised about how multifactor global change has affected food security and carbon sequestration capacity in China. By using a process-based ecosystem model, the Dynamic Land Ecosystem Model (DLEM), in conjunction with the newly developed driving information on multiple environmental factors (climate, atmospheric CO 2, tropospheric ozone, nitrogen deposition, and land cover/land use change), we quantified spatial and temporal patterns of net primary production (NPP) and soil organic carbon storage (SOC) across China's croplands during 1980-2005 and investigated the underlying mechanisms. Simulated results showed that both crop NPP and SOC increased from 1980 to 2005, and the highest annual NPP occurred in the Southeast (SE) region (0.32 Pg C yr -1, 35.4% of the total NPP) whereas the largest annual SOC (2.29 Pg C yr -1, 35.4% of the total SOC) was found in the Northeast (NE) region. Land management practices, particularly nitrogen fertilizer application, appear to be the most important factor in stimulating increase in NPP and SOC. However, tropospheric ozone pollution and climate change led to NPP reduction and SOC loss. Our results suggest that China's crop productivity and soil carbon storage could be enhanced through minimizing tropospheric ozone pollution and improving nitrogen fertilizer use efficiency.
  • Authors:
    • Chidthaisong, A.
    • Lu, Y.
    • Yuan, Q.
    • Klose, M.
    • Conrad, R.
  • Source: Soil Biology and Biochemistry
  • Volume: 49
  • Issue: June
  • Year: 2012
  • Summary: Straw amendment is a common practice for improving the fertility of rice field soils, but it also enhances production of the greenhouse gas methane. To quantify carbon flux partitioning and priming effects due to straw amendment, we measured delta C-13 in CH4 and CH4 precursors produced in anoxic slurries of soil from Italy, China and Thailand after addition of straw from either rice (C3 plant) or maize plants (C4 plant), which have different delta C-13 signatures. The delta C-13 values of the CH4, acetate and CO2 produced were similar when expressed as the difference to the delta C-13 value of the straw applied. These results indicated that the C-13-isotopic fractionation involved in methanogenic decomposition was similar for rice straw and maize straw. However, measurement of CH4 produced in soil without or with straw showed that isotopic fractionation during methanogenic degradation of straw was smaller than during degradation of soil organic matter. Isotopic fractionation during hydrogenotrophic methanogenesis, measured in the presence of methyl fluoride, with straw was also smaller than with soil organic matter. The results show that C-13-isotopic analysis after application of rice straw and maize straw is a convenient approach for quantifying carbon flux partitioning during methanogenic degradation of straw and soil organic matter. In our experiments, straw degradation accounted for most of the CH4 production and caused a negative priming effect on the methanogenic degradation of soil organic matter. (c) 2012 Elsevier Ltd. All rights reserved.
  • Authors:
    • Xiong, Z. Q.
    • Ma, Y. C.
    • Jia, J. X.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 150
  • Year: 2012
  • Summary: The net ecosystem carbon budget (NECB), global warming potential (GWP) and greenhouse gas intensity (GHGI) of vegetable ecosystems are not well documented. The net GWP and GHGI either including the carbon emissions from agricultural management (net mGWP/mGHGI) or not were estimated from an intensive vegetable production system in Nanjing, China between 2009 and 2010. The four typical consecutive rotations included celery-tung choy-baby bok choy-amaranth (C-T-Bb-A), choy sum-celery-tung choy-bok choy (Cs-C-T-Bc), garland chrysanthemum-tung choy-bok choy (G-T-Bc), and celery-choy sum-lettuce-bok choy (C-Cs-L-Bc). A net sink was observed and estimated at crop seasonal time scale for both the NECB and the soil organic carbon change (delta SOC) from the four vegetable rotation fields. The mGWP, net GWP, net mGWP. GHGI and mGHGI all showed nearly consistent changes among the rotations and among the vegetables within each rotation. The global warming potential ranged from 26 Mg CO2 equiv. ha(-1) to 109 Mg CO2 equiv. ha(-1) for net GWP and 36 Mg CO2 equiv. ha(-1) to 131 Mg CO2 equiv. ha(-1) for mGWP. The GHGI and mGHGI ranged from 0.17 kg CO2 equiv. kg(-1) vegetable to 0.41 kg CO2 equiv. kg(-1) vegetable and from 0.22 kg CO2 equiv.kg(-1) vegetable to 0.49 kg CO2 equiv. kg(-1) vegetable, respectively. The mGWP, net GWP, net mGWP, GHGI and mGHGI were dominated by the GWP resulting from N2O emissions. Annual cumulative direct N2O emissions were 374 kg N2O ha(-1) for G-T-Bc, 216 kg N2O ha(-1) for C-T-Bb-A, 159 kg N2O ha(-1) for Cs-C-T-Bc and 89 kg N2O ha(-1) for C-Cs-L-Bc, respectively. High N fertilizer input was likely responsible for the high N2O emissions. Increasing fertilizer use efficiency and adoption of best practices are effective measures for sustainable intensive vegetable production.
  • Authors:
    • Shan, W. H.
    • Jie, G. D.
    • Zhou, C. Z.
    • Mei, J. H.
  • Source: Acta Pedalogica Sinica
  • Volume: 49
  • Issue: 1
  • Year: 2012
  • Summary: Ammonia (NH 3) volatilization is a major pathway for gaseous nitrogen loss from fields applied with manure. To explore effects of topdressing of bio-digested manure slurry on ammonia volatilization, a field experiment was carried out in a vegetable greenhouse, applying bio-digested pig manure slurry (DPS) on winter vegetable, cress ( Oenanthe clecumbens L.) and radish ( Raphanus sativus L. Var. Radiculus pers.), and summer vegetable, pak choi ( Brassica chinensis L.) and crown daisy ( Chrysanthemum carinatum Schousb.). The topdressing rates of nitrogen were 72 kg hm -2, 54 kg hm -2, 42 kg hm -2 and 63 kg hm -2, respectively, during the growing periods of vegetables. Results showed that (1) topdressing of DPS led to explosion of ammonia volatilization within 48 h; (2) the accumulative ammonia release of the growing season reached 8.68 kg hm -2 and 9.90 kg hm -2 in cress and radish fields, respectively, which were significantly higher than those in the plots topdressing with chemical fertilizer (CF) (4.06 kg hm -2 and 5.59 kg hm -2); however, in the pak choi and crown daisy fields, the value was 10.40 kg hm -2 and 11.61 kg hm -2, respectively, which were not so significantly higher than those in the plots topdressing with CF (9.81 kg hm -2 and 10. 09 kg hm -2); (3) ammonia volatilization contributed 11.7% and 17.7% to the total N loss, respectively in the cress and radish plots topdressing with DPS in winter, and 23.3% and 26.8% in the pak choi and crown daisy plots in summer. The former was significantly lower than the latter; (4) temperature, water content, content of soluble organic carbon, form and concentration of nitrogen, biomass and activity of microbes in the surface soil at 0-10 cm depth were found to be the main contributors to ammonia volatilization. Application of bio-digested manure slurry in the vegetable field increased nitrogen loss through ammonia volatilization from DPS per se and its stimulative effect on decomposition of soil organic nitrogen. It is, therefore, essential to pay adequate attention to effects of temperature and application method in using bio-digested manure slurry as a soil amendment.