• Authors:
    • Kratochvil, R. J.
    • Forrestal, P. J.
    • Meisinger, J. J.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 1
  • Year: 2012
  • Summary: Evaluation of corn ( Zea mays L.) N management and soil residual NO 3-N late in the growing season could provide important management information for subsequent small grain crops and about potential NO 3-N loss. Our objective was to evaluate the ability of several late-season corn measurements, which have been advocated to assess N management, to identify sites with elevated soil residual NO 3-N. These crop-based measurements were collected at three reproductive phases and included normalized difference vegetative index (NDVI) at 10 site-years and green-leaf number and chlorophyll (SPAD) meter readings at six of these sites. The corn stalk nitrate test (CSNT) and postharvest soil residual NO 3-N were measured at all sites. Four levels of N were applied, ranging from N deficient (0 or 67 kg N ha -1) to excessive (269 kg N ha -1). The CSNT was positively ( p<0.001) correlated with residual NO 3-N, although residual NO 3-N was not always low at CSNT values <2.0 g NO 3-N kg -1, where drought reduced production. Drought stress was a major factor influencing excess N supply and residual soil NO 3-N. Canopy measurement values at growth stages R3-R4, including NDVI, which can be measured remotely, were effective indicators of drought stress. Across sites, relative canopy readings best predicted relative grain yield when collected at R3-R4, underscoring the importance of reference strips. Use of remotely measured NDVI would allow policymakers to identify drought sites in the late summer and target them for cover crop planting, thus reducing potential winter NO 3-N losses in humid regions.
  • Authors:
    • MacCarthy, D. S.
    • Fosu-Mensah, B. Y.
    • Vlek, P. L. G.
    • Safo, E. Y.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 94
  • Issue: 2-3
  • Year: 2012
  • Summary: Under low input subsistence farming systems, increased pressure on land use and decreased fallow periods have led to a decline in soil productivity. The soils in sub-humid region of Ghana are generally poor and require mineral fertilizer to increase crop productivity. This paper presents the use of Agricultural Production Systems sIMulator (APSIM) to simulate the long term influence of nitrogen (N) and phosphorus (P) on maize (Zea mays L.) yield in Sub-humid Ghana. The APSIM model was evaluated at two sites in Ejura, on a rainfed experiment carried out on maize in 2008 major and minor seasons, under various nitrogen and phosphorus rates. The model was able to reproduce the response of maize to water, N and P, and hence simulated maize grain yields with a coefficient of correlation (R-2) of 0.90 and 0.88 for Obatanpa and Dorke cultivars, respectively. A 21-year long term simulation, with different rates of N and P mineral fertilizer application, revealed that moderate application of N (60 kg N ha(-1)) and 30 kg P ha(-1) improves both the long term average and the minimum yearly guaranteed yield. Variability in grain yield increased with increasing application of N fertilizer in both seasons. Treatments with P fertilizer application shows a similar trend for the major season and reverse trend for the minor season, thereby suggesting an interactive effect with rainfall amounts and distribution. Application of 30 kg P ha(-1) significantly increased the response to N. The response to mineral fertilizer (N and P) applications varied between seasons, suggesting the need to have a range of fertilizer recommendations to be applied based on seasonal weather forecast.
  • Authors:
    • Munoz-Carpena, R.
    • Gabriel, J. L.
    • Quemada, M.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 155
  • Year: 2012
  • Summary: Using cover crops (CC) in semiarid irrigated areas is often limited by low nutrient and water-use efficiency. This work was conducted over 3.5 years to determine the effect on NO 3- leaching, water balance and soil mineral N accumulation of replacing fallow with CC in irrigated systems. Treatments studied during the maize ( Zea mays L.) intercrop period were: barley ( Hordeum vulgare L.), vetch ( Vicia villosa L.) and fallow. Soil water content was monitored daily to a depth of 1.3 m and used with the numerical model WAVE to describe the water balance. Determination of crop canopy parameters was based on digital image analysis, and root depth in capacitance sensor readings. Nitrate leaching was calculated multiplying drainage by the soil solution nitrate concentration. Soil mineral N was determined before sowing CC and maize. Over the study, cumulative nitrate leaching in the fallow, vetch, and barley was 346, 245, and 129 kg N-NO 3- ha -1, respectively; occurring more than 77% during the intercrop period. In dry winters, NO 3- accumulated in the topsoil, and CC controlled the NO 3- leaching during the initial maize growth stages. Vetch was less efficient than barley at controlling leaching, but enhanced soil N retention. The CC controlled NO 3- leaching and recycled N inside the cropping system.
  • Authors:
    • Ziadi, N.
    • Gagnon, B.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 6
  • Year: 2012
  • Summary: Residues from paper and wood mills are a valuable source of nutrients for field crops, but little is known about the effectiveness of repeated applications over many years. A study was initiated at Yamachiche, QC, to assess the effect of continuous applications over 9 yr of combined papermill biosolids (PB), applied alone or with several liming by-products, on grain yield, plant nutrient accumulation, and soil fertility in a loamy soil cropped to grain corn, dry bean, and soybean. The PB treatments (0, 30, and 60 Mg wet ha -1) and liming by-products [calcitic lime (CL), lime mud (LM), wood ash (WA)], and two magnesium residuals, each at 3 Mg wet ha -1 along with (30 Mg PB ha -1) were surface applied annually at post-seeding. In the last 6 yr, the two treatments receiving magnesium residuals were replaced with 90 Mg wet PB ha -1 and mineral N fertilizer (MIN), respectively. Repeated annual applications of LM followed by CL increased soil pH the most (up to 1.4 unit). Crop yields were not significantly affected by treatments in the first 3 yr but subsequent applications of PB at 90 Mg ha -1 increased yields in grain corn (+1.9 Mg ha -1) and dry bean (+0.77 Mg ha -1) relative to the control, while PB with WA increased yield in soybean (+0.85 Mg ha -1). The PB at 30 Mg wet ha -1 with supplemental N (average of 45 kg N ha -1), or at 60 Mg wet ha -1 applied alone, achieved yields comparable with MIN treatment under corn. The PB applications increased soil organic matter and all major soil nutrients except K and Mg. The results of this study indicate that PB and alkaline residuals can be effectively applied to agricultural soils over many years although PB exceeding 60 Mg wet ha -1 yr -1 induce significant nitrate leaching.
  • 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:
    • Lucas, S. T.
    • Weil, R. R.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 4
  • Year: 2012
  • Summary: Permanganate (KMnO 4) oxidizable C (POXC), an estimate of labile soil C, was evaluated for use as a soil test to identify soils that may respond positively to soil organic matter (SOM) management. We hypothesized that soils lower in POXC would be more likely than soils higher in POXC to show increased crop productivity in response to practices that increase SOM. At four sites, paired fields of the same soil but contrasting management history (cropping vs. sod) were studied. Fields with sod history tested higher in total organic C (TOC) and POXC than fields with cropped history. Permanganate-oxidizable C was strongly related to TOC ( r=0.94). We examined crop stover, grain, and biomass responses to two cover crop treatments within each field: winter rye ( Secale cereale L.) or no rye. After at least 1 yr of treatment, there was a significant negative correlation between relative stover response to rye and POXC ( r=-0.60) at sites with finer textured soils. After at least 2 yr of treatment, crop responses to rye showed a significant negative correlation with POXC and TOC. The strongest relationships to POXC occurred in the stover response at two sites with finer textured soils (Keedysville: r=-0.74; Holtwood: r=-0.84). Permanganate-oxidizable C was comparable to TOC at predicting crop responses to rye. These results suggest that POXC may be a useful test for identifying soils where improved SOM management is likely to improve productivity. The rapid, simple POXC methodology enables on-site or laboratory soil testing.
  • Authors:
    • Maltais-Landry, G.
    • Lobell, D. B.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 2
  • Year: 2012
  • Summary: Evaluating the contribution of weather and its individual components to recent yield trends can be useful to predict the response of crop production to future climate change, but different modeling approaches can yield diverging results. We used two common approaches to evaluate the effect of weather trends on maize ( Zea mays L.) and wheat ( Triticum aestivum L.) production in 12 U.S. counties, and investigate sources of disparities between the two methods. We first used the Decision Support System for Agrotechnology Transfer (DSSAT) model from 1984 to 2008 to evaluate the contribution of weather changes to simulated yield trends in six counties for each crop, each county being located in one of the top 10 U.S. producing states for that crop. A parallel analysis was conducted by multiplying inter-annual weather sensitivity of county-level yields with observed weather trends to estimate weather contributions to empirical yield trends. Weather had a low (maize) to high (wheat) contribution to simulated yield trends, with rain having the largest effect. In contrast, weather and rain had lower contributions to empirical yield trends. Along with evidence from previous studies, this suggests that DSSAT may be too sensitive to water thus inflating the importance of rain. Moreover, the time period used to compute yield trends also had a large effect on the importance of weather and its individual components. Our results highlight the importance of using multiple computation approaches and different time periods when estimating weather-related yield trends.
  • Authors:
    • Nyamangara, J.
    • Wuta, M.
    • Mapanda, F.
    • Rees, R. M.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 94
  • Issue: 1
  • Year: 2012
  • Summary: Agricultural efforts to end hunger in Africa are hampered by low fertilizer-use-efficiency exposing applied nutrients to losses. This constitutes economic losses and environmental concerns related to leaching and greenhouse gas emissions. The effects of NH4NO3 (0, 60 and 120 kg N ha(-1)) on N uptake, N-leaching and indirect N2O emissions were studied during three maize (Zea mays L.) cropping seasons on clay (Chromic luvisol) and sandy loam (Haplic lixisol) soils in Zimbabwe. Leaching was measured using lysimeters, while indirect N2O emissions were calculated from leached N using the emission factor methodology. Results showed accelerated N-leaching (3-26 kg ha(-1) season(-1)) and N-uptake (10-92 kg ha(-1)) with N input. Leached N in groundwater had potential to produce emission increments of 0-94 g N2O-N ha(-1) season(-1) on clay soil, and 5-133 g N2O-N ha(-1) season(-1) on sandy loam soil following the application of NH4NO3. In view of this short-term response intensive cropping using relatively high N rate may be more appropriate for maize in areas whose soils and climatic conditions are similar to those investigated in this study, compared with using lower N rates or no N over relatively larger areas to attain a targeted food security level.
  • 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:
    • Herrmann, A.
    • Techow, A.
    • Pacholski, A.
    • Quakernack, R.
    • Taube, F.
    • Kage, H.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 160
  • Year: 2012
  • Summary: Anaerobic co-fermentation of animal slurries and crop silages leads to new types of biogas residues with an uncertain fertilizer value. Ammonia volatilization losses and crop productivity after supplying co-fermented biogas residues were investigated at a marshland site in Northern Germany. Due to the ecological risks of monocultures, maize ( Zea mays) in monoculture as the dominant biogas crop in the marsh was tested against a crop rotation (maize, wheat ( Triticum aestivum), Italian ryegrass ( Lolium multiflorum)) and perennial ryegrass ( Lolium perenne). Biogas residues, applied by trail hoses, and CAN (mineral fertilizer) were used as nitrogen fertilizers. Ammonia losses at all application dates were investigated by an approach including passive flux samplers and a calibrated dynamic chamber method. Simultaneously a micrometeorological technique was used as a reference. A comparison of methods showed a close correlation ( r2=0.92) between micromet and passive flux sampler techniques. Ammonia volatilization losses (on average 15% NH 4+-N applied) occurred mainly within the first 10 h. Concomitant with high ammonia losses, a significant yield depression of 5 t DM ha -1 for ryegrass fertilized by biogas residues compared to CAN was observed. Little or no affect of biogas was observed for maize and wheat. The crop rotation had yields (34 t DM ha -1 2 year -1) that were comparable with the maize monoculture (31 t DM ha -1 2 year -1).