Legacy effects of long-term nitrogen fertilizer application on the fate of nitrogen fertilizer inputs in continuous maize

Poffenbarger, Hanna J.; Sawyer, John E.; Barker, Daniel W.; Olk, Daniel C.; Six, Johan; Castellano, Michael J.

doi:10.1016/j.agee.2018.07.005

Cited by 46 publications

(23 citation statements)

References 73 publications

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“…This region has experienced a change in land use patterns, with areas previously used for subsistence agricultural activities, such as upland rice farming, being converted to intensive agriculture for cash crops, such as banana, maize, and sugar canes [15]. While there is no information on the use of fertilizer in the region, nitrogen-based fertilizers have been known as necessary input for these cash crops to optimize yield [63]. Of the nine stations showing increasing nitrate trends, changes at six stations were statistically significant (p < 0.05), including the one detected at WLP.…”

Section: Seasonal Mann-kendall Analysis Of Historical Water Quality Tmentioning

confidence: 99%

Linking Changes in Land Cover and Land Use of the Lower Mekong Basin to Instream Nitrate and Total Suspended Solids Variations

Metternicht

Marshall

2020

Sustainability

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Population growth and economic development are driving changes in land use/land cover (LULC) of the transboundary Lower Mekong River Basin (LMB), posing a serious threat to the integrity of the river system. Using data collected on a monthly basis over 30 years (1985–2015) at 14 stations located along the Lower Mekong river, this study explores whether spatiotemporal relationships exist between LULC changes and instream concentrations of total suspended solids (TSS) and nitrate—as proxies of water quality. The results show seasonal influences where temporal patterns of instream TSS and nitrate concentrations mirror patterns detected for discharge. Changes in LULC influenced instream TSS and nitrate levels differently over time and space. The seasonal Mann–Kendall (SMK) confirmed significant reduction of instream TSS concentrations at six stations (p < 0.05), while nitrate levels increased at five stations (p < 0.05), predominantly in stations located in the upper section of the basin where forest areas and mountainous topography dominate the landscape. Temporal correlation analyses point to the conversion of grassland (r = −0.61, p < 0.01) to paddy fields (r = 0.63, p < 0.01) and urban areas (r = 0.44, p < 0.05) as the changes in LULC that mostly impact instream nitrate contents. The reduction of TSS appears influenced by increased forest land cover (r = −0.72, p < 0.01) and by the development and operation of hydropower projects in the upper Mekong River. Spatial correlation analyses showed positive associations between forest land cover and instream concentrations of TSS (r = 0.64, p = 0.01) and nitrate (r = 0.54, p < 0.05), indicating that this type of LULC was heavily disturbed and harvested, resulting in soil erosion and runoff of nitrate rich sediment during the Wet season. Our results show that enhanced understanding of how LULC changes influence instream water quality at spatial and temporal scales is vital for assessing potential impacts of future land and water resource development on freshwater resources of the LMB.

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Section: Seasonal Mann-kendall Analysis Of Historical Water Quality Tmentioning

confidence: 99%

Linking Changes in Land Cover and Land Use of the Lower Mekong Basin to Instream Nitrate and Total Suspended Solids Variations

Metternicht

Marshall

2020

Sustainability

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“…In highly fertile soils, N mineralized from SOM is typically the major source of crop N uptake (Stevens et al, 2005;Gardner and Drinkwater, 2009;Poffenbarger et al, 2018). If N fertilizer reduces SOM-N mineralization and, as a result, increases reliance on fertilizer N, it could increase environmental N losses because mineralized SOM-N is a more efficient source of crop N uptake (Drinkwater and Snapp, 2007).…”

Section: The Net Effect Of N Fertilizer On Ecosystem Nuementioning

confidence: 99%

Nitrogen Fertilizer Suppresses Mineralization of Soil Organic Matter in Maize Agroecosystems

et al. 2019

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The possibility that N fertilizer increases soil organic matter (SOM) mineralization and, as a result, reduces SOM stocks has led to a great debate about the long-term sustainability of maize-based agroecosystems as well as the best method to estimate fertilizer N use efficiency (FNUE). Much of this debate is because synthetic N fertilizer can positively or negatively affect SOM mineralization via several direct and indirect pathways. Here, we test a series of hypotheses to determine the direction, magnitude, and mechanism of N fertilizer effect on SOM mineralization and discuss the implications for methods to estimate FNUE. We measured the effect of synthetic N fertilizer on SOM mineralization via gross ammonification at two long-term experiments in central and southern Iowa, USA with replicated plots of continuous maize that received one of three "historical" N fertilizer rates (zero, moderate or high) from 1999 to 2014. In 2015, prior to our measurements, we split the historical N fertilizer rate plots into two subplots that received either the site-specific agronomic optimum N rate or zero N fertilizer. At the onset of rapid maize N uptake, N fertilizer reduced gross ammonification by 13-21% (2-5 kg NH 4-N ha −1 d −1). A companion laboratory experiment rejected the hypothesis that differences in net primary productivity between fertilized and unfertilized treatments explained the negative effect of N fertilizer on SOM mineralization. Moreover, the NH + 4 pool size was negatively correlated with the gross ammonification rate (r 2 = 0.85, p < 0.001). Thus, we conclude that NH + 4-N fertilizer had a direct suppressive effect on SOM mineralization. These results demonstrate that the direct effect of N fertilizer on microbial activity can exceed the indirect effects of N fertilizer via large changes in NPP that alter organic matter inputs, soil temperature and moisture content. The magnitude of this effect and specificity to NH + 4-N has significant implications for fertilizer management as well as the measurement and modeling of agroecosystem N dynamics including FNUE.

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“…In non-agricultural lands, the largest N source for plant and microbe uptake and loss from system derive from mineralization of SON [59]. Rapid decomposition of SON leads to 15 N enrichment in the remaining SOM and mycorrhizal fungi [60].…”

Section: Fractionation Of C and N Isotopic In Decomposition Transformentioning

confidence: 99%

Variations and Indications of δ13CSOC and δ15NSON in Soil Profiles in Karst Critical Zone Observatory (CZO), Southwest China

et al. 2019

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Soil carbon and nitrogen storage and stabilization are the key to solving the problems of mitigation of global warming and maintaining of crop productivity. In this study, the contents of soil organic carbon (SOC) and soil organic nitrogen (SON) and their stable isotope compositions (δ13CSOC and δ15NSON) in soil profiles were determined in two agricultural lands (including a farmland and an abandoned farmland) and four non-agricultural lands (including two shrub-grass lands and two shrub lands) in the karst critical zone observatory (CZO), Southwest China. The contents of SOC and SON were used for research on the effects of land use on SOC and SON storage, and the change of δ13CSOC and δ15NSON values in soil profiles were used to indicate SOC and SON stabilization. The results showed that agricultural activities reduced SOC and SON storage in the whole soil layers of farmland compared to non-agricultural lands, and farmland abandonment slightly increased SOC and SON storage. Crop rotation between peanut (C3) and corn (C4) affected the δ13CSOC in surface soils of agricultural lands (−21.6‰), which were intermediate between shrub lands (−22.7‰) and shrub-grass lands (−19.6‰). 15N-depleted SON in surface soils in farmland compared to those soil in other lands possibly associated with synthetic N fertilizer application. In soil layers below 30 cm depth the δ13CSOC deceased with depth, while the δ15NSON displayed irregular fluctuation. The change in δ13CSOC and δ15NSON through soil profiles in karst soils were more intensive than those in semiarid grassland soils indicating the less stabilization of SOC and SON in karst soils.

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Legacy effects of long-term nitrogen fertilizer application on the fate of nitrogen fertilizer inputs in continuous maize

Cited by 46 publications

References 73 publications

Linking Changes in Land Cover and Land Use of the Lower Mekong Basin to Instream Nitrate and Total Suspended Solids Variations

Linking Changes in Land Cover and Land Use of the Lower Mekong Basin to Instream Nitrate and Total Suspended Solids Variations

Nitrogen Fertilizer Suppresses Mineralization of Soil Organic Matter in Maize Agroecosystems

Variations and Indications of δ13CSOC and δ15NSON in Soil Profiles in Karst Critical Zone Observatory (CZO), Southwest China

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