• Authors:
    • van der Werf, W
    • Zhang, F. S.
    • Six, J.
    • Cong, W. F.
    • Hoffland, E.
    • Li, L.
    • Sun, J. H.
    • Bao, X. G.
  • Source: GLOBAL CHANGE BIOLOGY
  • Volume: 21
  • Issue: 4
  • Year: 2015
  • Summary: Intercropping, the simultaneous cultivation of multiple crop species in a single field, increases aboveground productivity due to species complementarity. We hypothesized that intercrops may have greater belowground productivity than sole crops, and sequester more soil carbon over time due to greater input of root litter. Here, we demonstrate a divergence in soil organic carbon (C) and nitrogen (N) content over 7 years in a field experiment that compared rotational strip intercrop systems and ordinary crop rotations. Soil organic C content in the top 20 cm was 4%1% greater in intercrops than in sole crops, indicating a difference in C sequestration rate between intercrop and sole crop systems of 18486 kg C ha -1 yr -1. Soil organic N content in the top 20 cm was 11%1% greater in intercrops than in sole crops, indicating a difference in N sequestration rate between intercrop and sole crop systems of 4510 kg N ha -1 yr -1. Total root biomass in intercrops was on average 23% greater than the average root biomass in sole crops, providing a possible mechanism for the observed divergence in soil C sequestration between sole crop and intercrop systems. A lowering of the soil delta 15N signature suggested that increased biological N fixation and/or reduced gaseous N losses contributed to the increases in soil N in intercrop rotations with faba bean. Increases in soil N in wheat/maize intercrop pointed to contributions from a broader suite of mechanisms for N retention, e.g., complementary N uptake strategies of the intercropped plant species. Our results indicate that soil C sequestration potential of strip intercropping is similar in magnitude to that of currently recommended management practises to conserve organic matter in soil. Intercropping can contribute to multiple agroecosystem services by increased yield, better soil quality and soil C sequestration.
  • Authors:
    • Verhallen, E. A.
    • Hayes, A.
    • Congreves, K. A.
    • Van Eerd, L. L.
  • Source: Soil and Tillage Research
  • Volume: 152
  • Year: 2015
  • Summary: Long-term agricultural production with different tillage systems and crop rotations affect soil health, and thereby influence agricultural sustainability. However, quantifying and integrating the numerous soil health attributes is complex. One method of measuring overall soil health is the Cornell Soil Health Assessment (CSHA) used in New York; however, its applicability for other regions should be evaluated. Soil samples were collected from the 0-15. cm depth in 2009 and 2010 at four temperate, rainfed long-term experimental sites in Ontario (Ridgetown, Delhi, Elora, and Ottawa) and we evaluated the impact of tillage systems and crop rotations on 15 soil attributes. Based on a principal component analysis (PCA), the first two components accounted for 62% of the cumulative variability. The PCA eigenvectors were used to weight individual CSHA scores and develop the new Ontario Soil Health Assessment (OSHA) overall score. The OSHA scoring system was 2-10 times more sensitive than the CSHA in showing numerical differences for soil health among different tillage systems and crop rotations, which may help growers to more clearly see differences in soil health under different management practices. No-till (NT) compared to conventional tillage (CT) had significantly greater OSHA scores at Ridgetown, Delhi, and Elora, but there was no difference at Ottawa. At Ridgetown and Elora, crop rotations which included winter wheat or alfalfa tended to have higher OSHA scores, while lowest scores were with monoculture corn (monoC) or soybean-corn (S-C or S-S-C-C). This study provides the first soil health assessment for Ontario and a framework for improving overall soil health testing elsewhere.
  • Authors:
    • Dash, J.
    • Duncan, J. M. A.
    • Atkinson, P. M.
  • Source: GLOBAL CHANGE BIOLOGY
  • Volume: 21
  • Issue: 4
  • Year: 2015
  • Summary: Remote sensing-derived wheat crop yield-climate models were developed to highlight the impact of temperature variation during thermo-sensitive periods (anthesis and grain-filling; TSP) of wheat crop development. Specific questions addressed are: can the impact of temperature variation occurring during the TSP on wheat crop yield be detected using remote sensing data and what is the impact? Do crop critical temperature thresholds during TSP exist in real world cropping landscapes? These questions are tested in one of the world's major wheat breadbaskets of Punjab and Haryana, north-west India. Warming average minimum temperatures during the TSP had a greater negative impact on wheat crop yield than warming maximum temperatures. Warming minimum and maximum temperatures during the TSP explain a greater amount of variation in wheat crop yield than average growing season temperature. In complex real world cereal croplands there was a variable yield response to critical temperature threshold exceedance, specifically a more pronounced negative impact on wheat yield with increased warming events above 35°C. The negative impact of warming increases with a later start-of-season suggesting earlier sowing can reduce wheat crop exposure harmful temperatures. However, even earlier sown wheat experienced temperature-induced yield losses, which, when viewed in the context of projected warming up to 2100 indicates adaptive responses should focus on increasing wheat tolerance to heat. This study shows it is possible to capture the impacts of temperature variation during the TSP on wheat crop yield in real world cropping landscapes using remote sensing data; this has important implications for monitoring the impact of climate change, variation and heat extremes on wheat croplands.
  • Authors:
    • Gan, Y. T.
    • Cui, H. Y.
    • Yin, W.
    • Yu, A. Z.
    • Chai, Q.
    • Hu, F. L.
  • Source: AGRONOMY FOR SUSTAINABLE DEVELOPMENT
  • Volume: 35
  • Issue: 2
  • Year: 2015
  • Summary: Intercropping is used to increase grain production in many areas of the world. However, this increasing crop yield costs large amounts of water used by intercropped plants. In addition, intercropping usually requires higher inputs that induce greenhouse gas emissions. Actually, it is unknown whether intercropping can be effective in water-limited arid areas. Here, we measured crop yield, water consumption, soil respiration, and carbon emissions of wheat-maize intercropping under different tillage and crop residue management options. A field experiment was conducted at Wuwei in northwest China in 2011 and 2012. Our results show that wheat-maize intercropping increased grain yield by 61 % in 2011 and 63 % in 2012 compared with the average yield of monoculture crops. The intercropping under reduced tillage with stubble mulching yielded 15.9 t ha(-1) in 2011 and 15.5 t ha(-1) in 2012, an increase of 7.8 % in 2011 and 8.1 % in 2012, compared to conventional tillage. Wheat-maize intercropping had carbon emission of 2,400 kg C ha(-1) during the growing season, about 7 % less than monoculture maize, of 2,580 kg C ha(-1). Reduced tillage decreased C emission over conventional tillage by 6.7 % for the intercropping, 5.9 % for monoculture maize, and 7.1 % for monoculture wheat. Compared to monoculture maize, wheat-maize intercropping used more water but emitted 3.4 kg C per hectare per millimeter of water used, which was 23 % lower than monoculture maize. Overall, our findings show that maize-wheat intercropping with reduced tillage coupled with stubble mulching can be used to increase grain production while effectively lower carbon emissions in arid areas.
  • Authors:
    • Lemke, R. L.
    • Drury, C. F.
    • Smith, W. N.
    • Yang, J. Y.
    • Li, Z. T.
    • Grant, B.
    • He, W. T.
    • Li, X. G.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 101
  • Issue: 3
  • Year: 2015
  • Summary: The overall performance of the Decision Support System for Agrotechnology Transfer-Cropping System Model (DSSAT-CSM) was evaluated for simulating wheat (Triticum aestivum L.) yield, grain N uptake, soil organic C (SOC) and N (SON), soil water and nitrate-N (NO3-N) dynamics. The data used was from a long-term (1967-2005) spring wheat experiment conducted at Swift Current, Saskatchewan in the semi-arid Canadian prairies. Four treatments were selected: (1) continuous wheat receiving N and P fertilizer, Cont-W(NP); (2) continuous wheat receiving P only, Cont-W(P); and each phase of a fallow wheat rotation receiving N and P fertilizer, (3) W-F(NP) and (4) F-W(NP). The simulated grain yields matched the measurements well, with high d (0.74-0.83) and EF (0.16-0.33). The grain N uptake was also simulated satisfactorily with RMSE of 14-17 kg N ha(-1) and d of 0.66-0.81. DSSAT simulated topsoil (0-0.15 m) SOC and SON well in the drier period (1967-1991), whereas it underestimated SOC in the more humid period (1991-2003). The DSSAT successfully simulated soil water and NO3-N dynamics in 0-0.15 m depth, whereas it overestimated soil water and NO3-N in the deep layers and consequently underestimated NO3-N leaching, suggesting that further improvements in soil water module should be made for the semi-arid climatic conditions in Canadian prairies. Sensitivity results showed that soil water content was sensitive to both lower soil water and upper drainage limits in this study. The performances of DSSAT model to yield and soil dynamics were comparable with other models.
  • Authors:
    • Lambert, D. M.
    • Thierfelder, C.
    • Hicks, B. B.
    • Sauer, T. J.
    • O'Dell, D.
    • Logan, J.
    • Eash, N. S.
  • Source: Journal of Agricultural Science (Toronto)
  • Volume: 7
  • Issue: 3
  • Year: 2015
  • Summary: Two of the biggest problems facing humankind are feeding an exponentially growing human population and preventing the accumulation of atmospheric greenhouse gases and its climate change consequences. Refined agricultural practices could address both of these problems. The research addressed here is an exploration of the efficacy of alternative agricultural practices in sequestering carbon (C). The study was conducted in Zimbabwe with the intent to (a) demonstrate the utility of micrometeorological methods for measuring carbon dioxide (CO 2) exchange between the surface and the atmosphere in the short-term, and (b) to quantify differences in such exchange rates for a variety of agricultural practices. Four Bowen ratio energy balance (BREB) systems were established on the following agricultural management practices: (1) no-till (NT) followed by planting of winter wheat ( Triticum aestivum), (2) NT followed by planting of blue lupin ( Lupinus angustifolios L.), (3) maize crop residue ( Zea mays L.) left on the surface, and (4) maize crop residue incorporated with tillage. Over a period of 139 days (from 15 June to 31 October 2013) the winter wheat cover crop produced a net accumulation of 257 g CO 2-C m -2, while the tilled plot with no cover crop produced a net emission of 197 g CO 2-C m -2 and the untilled plot with no cover emitted 235 g CO 2-C m -2. The blue lupin cover crop emitted 58 g CO 2-C m -2, indicating that winter cover crops can sequester carbon and reduce emissions over land left fallow through the non-growing season. The micrometeorological methods described in this work can detect significant differences between treatments over a period of a few months, an outcome important to determine which smallholder soil management practices can contribute towards mitigating climate change.
  • Authors:
    • Reeve, J. R.
    • Jacobson, A. R.
    • Endelman, J. B.
    • Olsen, D. J. R.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 101
  • Issue: 3
  • Year: 2015
  • Summary: Compost plays a central role in organic soil fertility plans but is bulky and costly to apply. Determining compost carryover is therefore important for cost-effective soil fertility planning. This study investigated two aspects of nutritive carryover [nitrogen and phosphorus (P)], and an indicator of non-nutritive carryover [soil organic matter (SOM)] to determine the residual effect of a one-time compost application applied at four rates in a corn-squash rotation. Crop yield was measured as an integrated carryover indicator of nutritive and non-nutritive effects. Functional groups of compost and SOM were investigated using FT-IR spectroscopy and soil organic carbon (SOC). While year to year variability was great, compost had a persistent positive effect on crop yields, evident 3 years after application with no reduction in magnitude over time. Soil nitrate was low, and additions of compost at any rate generally did not increase levels beyond the year of application, with the exception of year four. Olsen P was also low, yet was higher in amended soils than in non-amended soils 3 years after application. Pronounced polysaccharide peaks, evident in compost spectra and absent in control soil, were apparent in compost-amended soils 3 years after compost treatment and SOC was greater 2 years afterwards. Compost carryover was most pronounced in year four following the incorporation of a nitrogen-fixing cover crop. These results show that compost can influence nutritive and non-nutritive soil properties many years after incorporation, thereby reinforcing the importance of including compost in organic fertility plans despite the unpredictability of year-to-year response.
  • Authors:
    • Singh, A.
    • Singh, S.
    • Agrawal, S. B.
    • Agrawal, M.
    • Singh, P.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 199
  • Year: 2015
  • Summary: The effects of ambient ozone (O 3) on wheat ( Triticum aestivum L.) varieties HUW 510 and LOK-1 were studied at recommended and 1.5 times recommended NPK under natural field conditions using open top chambers under varying NPK levels. Ambient O 3 was filtered out from air through charcoal filters for control plants (FCs), while non-filtered chambers received ambient O 3 (NFCs). Twelve hourly mean concentrations of O 3 varied from 10.3 to 110 ppb. Plants growing in FCs showed better growth performance and higher biomass accumulation compared to those in NFCs at both NPK levels. There were improvements in yield and its quality parameters in FCs compared to NFCs at both NPK levels with no significant difference in yield between FCs and NFCs at 1.5 times recommended NPK in LOK-1 and at RNPK in HUW 510. Nitrogen utilization efficiency increased in NFCs compared to FCs in both the varieties, but lower capability of N acquisition under ambient O 3 led to higher magnitude of reduction in yield of LOK-1 compared to HUW 510 at recommended NPK. The results clearly showed that 1.5 times recommended NPK alleviated the negative effects of ambient O 3 pollutant in LOK-1 variety whereas recommended NPK in HUW 510.
  • Authors:
    • Novak, J. M.
    • Cantrell, K. B.
    • Hunt, P. G.
    • Stone, K. C.
    • Sigua, G. C.
  • Source: AGRONOMY FOR SUSTAINABLE DEVELOPMENT
  • Volume: 35
  • Issue: 2
  • Year: 2015
  • Summary: Biochar is a black solid formed by pyrolysis of biomass such as crop residues. Biochar could be used for soil fertilization, carbon sequestration, and improvement of soil structure. Here, we tested the effect of sorghum biochars on winter wheat, with or without supplemental inorganic phosphorus, in a greenhouse. The application rate for sorghum residues and sorghum biochars based on a yield goal of 200 bushels ha(-1) was 13 Mg ha(-1). Inorganic phosphorus was added at the rate of 40 kg P ha(-1). Results show that addition of sorghum biochars increased the total biomass of winter wheat grown by about 31 % over the control plants. Addition of supplemental inorganic phosphorus did not increase the total biomass. Our findings suggest that the pyrolitic transformation of sorghum residues into sorghum biochars is a better strategy for both environmental and crop productivity improvement in the Coastal Plains region.
  • Authors:
    • Valentine, T. A.
    • Hawes, C.
    • Squire, G. R.
    • Young, M. W.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 202
  • Year: 2015
  • Summary: Efforts to maintain or increase food production in developed agriculture would be compromised if current high-intensity production was degrading supporting ecosystem services, such as the ability of soil to function. The link between cropping intensity, defined by pesticide and fertiliser applications, and soil biophysical status was examined at 70 sites in a high-yielding region of the UK, in which cropping sequences covering a wide range of intensity had diverged from a common low-intensity origin in the 1970s. Two sequences of still low or moderate intensity based on spring cereals or a low frequency of winter cereals formed comparators for three high intensity sequences based on winter wheat and potato which together were associated with adverse effects of -30% on soil carbon content in the upper soil layer ( P<0.001), -11% on soil water holding capacity ( P<0.01) and +15% on soil bulk density ( P<0.001). Negative effects were also found in some high intensity sequences on soil macroporosity and penetrometer resistance. Even in this high-yielding region, therefore, current forms of intensification are associated with adverse trends in soil condition that may be detrimental to future production. The effects of these trends in soil condition on agricultural output now need to be quantified, and the economic burden accounted for, if fields reduce their capacity to yield or need reparation to keep them productive.