Pattern Of Grains Research Articles

The study of grain transport effects on grain refinement under pulsed magnetic fields

The motion of grains within the molten metal under a pulsed magnetic field influences the influx of grains, thereby impacting the refinement of the solidification structure of metal. Physical simulation experiments, solidification studies, numerical simulations, and theoretical analyses are combined to investigate the motion patterns of grains in molten metal subjected to a pulsed magnetic field in the case of identical power. The findings suggest that grain movement occurs in two primary phases: initially, within the non-flow area at the solid-liquid interface, where grains respond to electromagnetic forces, and subsequently, within the flow area where the molten metal carries the grains. The speed of grain transport in the flow area directly influences the movement of grains in the non-flow area, then affecting the refinement of the metal solidification structure. The study introduces the concept of "transport characteristic time" to quantify the transport capacity of grains within the flow area, which enables a quantitative analysis of refinement effect under identical power conditions.

An Extraterrestrial Pt Anomaly during the Late Glacial-Younger Dryas: Viso Massif (Italy and France)

Paleosol evidence supporting the Younger Dryas Impact Hypothesis (YDIH) on the Viso Massif of France and Italy is expanded by a Pt anomaly at all sites investigated, accompanied by elevated Os, Ir, Ru, and Rh concentrations at several sites, thus affirming a cosmic driver to the YD climatic shift at 12.8 ka. Original, thin Allerød soils prevalent at the end of the Late Glacial comprise sediments affected by an airburst from a hypothesized secondary daughter fragment or fragments of the main 2P/Encke progenitor comet train that intersected Earth’s land surface and its alpine-continental ice sheets. This event has been previously postulated to have breached Lake Agassiz and other proglacial lakes in North America, released meltwater into the Atlantic Ocean through the St. Lawrence and into the Arctic through the Mackenzie River system, after which cold surface water shut down the thermohaline circulation of the Gulf Stream in the North Atlantic. This thermohaline event is the traditional explanation for YD cooling, but was it fast enough to match the pollen evidence, which confirms rapid temperature reversal? Or was an “impact winter” involved? Cosmic signatures reported here include elevated Pt/Pd ratios, Os, Ir, Ru, and Rh concentrations with orders of magnitude (OM) for Ir used to establish the main center of conflagrations that helped trigger an impact winter. While most sections show variable distributions of PGEs, some are fully affected by concentrations entirely through the unweathered substrate or parent material horizons (called “Cu” horizons). Peak distributions of platinum group elements (PGEs) provide new information on the dispersal patterns of grains that add the Western European Alps to the intercontinental array of sites containing the Younger Dryas boundary (YDB) layer, also sometimes called the black mat (BM). Previously, most age determinations for the Alps were derived from relative dating determinations (RD), but here, we report an AMS C14 date from one LG paleosol (G11-Bw) yielding an age of 12,816 ±44 cal yr BP age, coeval with the average 12.8 ka age of the BM.

Hardness and Microstructure Analysis of Rotary Friction Welded Dissimilar Joint of Cu and Ti-6Al-4V

In this paper, the effect of rotary friction welding on hardness and microstructures of weld zones and base metal zones of Ti-6Al-4V and Cu have been investigated. A rotary friction welding technique was used to perform dissimilar joining of Cu and Ti-6Al-4V bars. Friction welding process parameters were optimized process parameters of a 5-ton rotary friction welding machine. The upset pressures were applied from 30 kg/mm2, 40 kg/mm2 and 50 kg/mm2. The dissimilar joint was successfully formed at upset pressure of 50 kg/mm2. The friction welded joints were failed in drop test after welding at the lower upset pressures (30 kg/mm2 and 40 kg/mm2).The hardness and microstructures were characterized for weld joint formed at 50 kg/mm2. The weld zone, base metal and weld interface and base metals were analysed to understand microstructures and elemental diffusion of Ti and Cu. The welded specimens were examined by using an optical microscope and scanning electron microscope. Grain refinement was seen in Cu near the interface of the joint whereas in the case of titanium circular patterns of grains were seen near the interface of the joint. The micro hardness of Ti-6Al-4V was increased from 307 HV to 365 HV and for Cu increased from 240 HV to 290 HV. Intermetallic compounds such TiCu4 and Ti2Cu were found at weld zone by X-ray diffraction analysis.

Ethylene sensitivity underscores the yield advantage of high-grain numbers in cylinder-shaped rice panicles

Panicle-wise grain-filling of individual spikelets is location-specific in rice; apical spikelets dominate over their basal counterparts. This pattern of grain filling changes with panicle architecture among cultivars, but the underlying mechanisms are not understood. The newly introduced rice cultivars with cylinder-shaped panicles, although suited for high yield, exhibit several instances of poor filling. In this study shoot apical meristem gene expressions in the ontogeny stage and their influence on spikelet survival at the post-anthesis stage were elucidated by screening two types of rice Recombinant Inbreed Lines (RIL) having similar spikelet density in the cylinder-shaped panicles, such as SR-157 (low-sterile) and SR-159 (high-sterile) and their parents NPT-V12 (low-sterile) and SPS-1–6–1 (high-sterile). Between cultivars, SR-157 versus SR-159, and spikelets located apically versus basally, grain filling was more vulnerable in the latter than the former owing to a more remarkable evolution of ethylene at anthesis. Combined genome analyses revealed that branching genes like DEP2, SPL-14, PTR, and FZP over-expressed in high-sterile compared to low-sterile cultivars during the ontogeny stage. But this over-expression had no matching improvement in grain-setting in the post-anthesis stage. Grain starch synthesis was higher, and expression of ethylene receptors and signal transducer genes was lower in the low- compared to high-sterile cultivars. Thus, the quantum of grain set in the post-anthesis stage determining actual panicle yield was not dependent on the expression of genetic factors in the pre-anthesis stage defining potential grain yield. It was concluded that the default expression of ethylene synthesis and transducer genes at anthesis cause spikelet degeneration and deride the yield advantage of a high spikelet number in some cylinder-shaped rice panicles. The genomic studies controlling ethylene evolution and action in rice panicles must be an inalienable part of any constructive contribution to the yield potential.

Measurement and spatio-temporal transfer of greenhouse gas emissions from agricultural sources in China: A food trade perspective

The transfer characterization of greenhouse gas from agricultural sources in the food trade is important to ensure food security and mitigate climate change. In this study, a spatial equilibrium model was established to simulate the trade flow patterns of grains and meat in China from 2000 to 2020 and the greenhouse gas from agricultural sources implied therein. This identified coupling relationship between production and greenhouse gas emissions. The results showed that the separation of supply and demand in food trade led to greenhouse gas transfers and flows that were similar to the food trade pattern. The total greenhouse gas transfer from grains decreased. However, that from meat increased from 13.91 Mt CO2-eq to 41.89 Mt CO2-eq, while the cross-regional transfer share increased from 47.86% to 59.16%. This study provides a benchmark for the better formulation of policies for zonal greenhouse gas reduction from agricultural sources.

Scales and spatial distribution patterns of grain reserves on the Qinghai-Tibet Plateau

Scales and spatial distribution patterns of grain reserves on the Qinghai-Tibet Plateau

Designing rice panicle architecture via developmental regulatory genes.

Rice panicle architecture displays remarkable diversity in branch number, branch length, and grain arrangement; however, much remains unknown about how such diversity in patterns is generated. Although several genes related to panicle branch number and panicle length have been identified, how panicle branch number and panicle length are coordinately regulated is unclear. Here, we show that panicle length and panicle branch number are independently regulated by the genes Prl5/OsGA20ox4, Pbl6/APO1, and Gn1a/OsCKX2. We produced near-isogenic lines (NILs) in the Koshihikari genetic background harboring the elite alleles for Prl5, regulating panicle rachis length; Pbl6, regulating primary branch length; and Gn1a, regulating panicle branching in various combinations. A pyramiding line carrying Prl5, Pbl6, and Gn1a showed increased panicle length and branching without any trade-off relationship between branch length or number. We successfully produced various arrangement patterns of grains by changing the combination of alleles at these three loci. Improvement of panicle architecture raised yield without associated negative effects on yield-related traits except for panicle number. Three-dimensional (3D) analyses by X-ray computed tomography (CT) of panicles revealed that differences in panicle architecture affect grain filling. Importantly, we determined that Prl5 improves grain filling without affecting grain number.

Microstructure Evolution of AZ91 Magnesium Alloy Welded Joint under Magnetic Field and NiCl2 Activated Flux

As the lightest engineering materials, magnesium alloys have been widely used. Because of the specific chemical and physical characteristics, the weldability of magnesium alloy is poor. Adopting suitable welding technology and improving the quality of magnesium alloy welded joints is key to their successful application. According to previous research data, it was found that the combined action of magnetic field and activated flux has a positive effect on improving-welding efficiency and improving the properties of a welded joint, butanalysis of microstructure evolution is insufficient. In this paper, AZ91 magnesium alloy was welded by TIG welding with activated flux and external longitudinal AC magnetic field. The phase composition and microstructure evolution were investigated. The experimental results revealed that the phase composition of welded joint was not changed due to the introduction of the magnetic field and activated flux, the growth patterns of grain in the weld seam and heat-affected zone were different. When the activated flux amount was 3 mg/cm2 with the effect of the magnetic field, the grain size of the weld seam was the finest, which was 18.96 μm. However, the grain size of the weld seam was larger than that of base metal. The crystallographic characteristics of grain boundaries in the weld seam and base metal were both LAGBs. The microstructure of the weld seam was messier than the base metal due to the larger misorientation angle. Under the combined action of the magnetic field and activated flux, the crystallization nucleation condition of the molten pool was changed, the formation of twins was promoted, and the crystal could selectively grow parallel with the (0001) basal plane.

Impact of Climate Change and Technology on Food Availability in Sumatera, Indonesia


 This study explores the impact of climate change and technology on food supply and demand, which complements the limits of previous findings. The main foundations are Hessian food production and Marshallian demand theories. It aims to analyze the factors influencing food availability and the response of each variable, as well as simulate the effect of climate change and technology. Secondary data from the Food Security and the Central Statistics Agency of 10 provinces in Sumatra will be used between the periods of 2010 to 2019. Furthermore, this study uses the simultaneous method of 8 structural and 2 identity equations. The influencing variables of production include price, expected food pattern of grains and tubers, CPO price, temperature, rainfall, and irrigation network area. Meanwhile, consumption is influenced by price, poverty, food inflation, population, per capita income, and farmers’ exchange rate. The increase in temperature and rainfall reduces the production and consumption of rice, corn, cassava, and sweet potatoes. Meanwhile, technology development will increase food production and consumption. The availability is an essential dimension of food security that should be prioritized. Likewise, climate change and technology development need to be anticipated to mitigate these impacts.

Analyses of True-Triaxial Hydraulic Fracturing of Granite Samples for an Enhanced Geothermal System

Abstract The fracturing behavior of enhanced geothermal system (EGS) reservoirs merits investigation under field-relevant temperature and stress conditions, in order to understand the creation of an extensive fracture network that helps achieve a high heat exchange efficiency. In this work, hydraulic fracturing tests were conducted on two 300 mm sized cubic granite samples at room (32°C) and field-relevant (250°C) temperatures under true triaxial compression conditions. The failure behavior and fracturing plane were studied using acoustic emission (AE) testing, μm-scale computed tomography (μm-CT), and scanning electronic microscopy (SEM), in addition to the monitoring and analyses of pressure-flow curve during fracturing. The results show that (1) at the macroscale, the strength of the granite sample was weakened at high (field-relevant) temperature, as shown by a decrease in the breakdown pressure and increase in closure pressure from the pressure-flow curve; (2) at the microscale, the failure pattern of grains during fracturing did not differ much at high and room temperatures for both intergranular and transgranular fractures; and (3) due to upscaling issues from the laboratory to field, however, the laboratory experiment will not directly provide some critical parameters (e.g., mud window pressure needed for fracture initiation and borehole failure avoidance) needed for an EGS field exploration.

Impact of Thermal Treatment on the Surface of Na0.5Bi0.5TiO3-Based Ceramics

Thermal etching is a widely accepted surface treatment method for studying microstructure in Na0.5Bi0.5TiO3-based compositions. Surprisingly, besides the flat pattern of grains (suitable for evaluating ceramics’ microstructure), images illustrating well-expressed relief and even microstructure consisting of partly bonded cubic-shaped grains are also found among the micrographs presented in various publications. The present paper shows that this different surface character in Eu-modified Na0.5Bi0.5TiO3 can be obtained through thermal treatment across a wide range of temperatures. At higher temperatures, remarkable growth of cubic-shaped grains on the surface is observed. This growth affects the grain size distribution on the surface more than it does within the bulk of a sample. Such micrographs cannot be used to characterise the microstructure of dense ceramics. Intensive growth of TiO2 inclusions at high thermal treatment temperatures is also observed, revealing substantial evaporation of Bi and Na from the surface of a ceramic sample, but not from its core part.

Prolificacy and nitrogen internal efficiency in maize crops

Abstract In maize (Zea mays L.) crop, “defensive practices” such as low plant densities and limited nitrogen (N) fertilization have begun to be progressively adopted in limited-production regions of the world. At low plant density, the expression of prolificacy (i.e., more than one fertile ear per plant) can stabilize maize production. Considering N as the main limiting resource, yield can be defined as a function of i) total N uptake and the efficiency to produce yield from total N uptake, i.e., N internal efficiency (NIE) or ii) total N uptake, N harvest index (NHI) and grain N concentration. The objective of this work was to describe changes in NIE and their related components regulated by prolificacy at both canopy- and plant- scales. Field studies were carried out in Buenos Aires, Argentina, during 2015–2016 and 2016–2017 seasons. Treatments were combinations of two N supplies (N-: 0 and N+: 200 kg N ha−1), two plant densities (4 and 8 plants m−2) and five maize hybrids released during the last four decades. High N supply positively impacted yield per unit area (ca. 45 %) by increasing kernel number (ca. 33 %), kernel weight (ca. 18 %) and harvest index (ca. 12 %). At low plant density, high N supply expressed the highest prolificacy (mean 1.65 ears plant−1). The older hybrids displayed the highest prolificacy (mean 1.30 ears plant−1) and the lowest yield per unit area (mean 792 g m−2), but showed the greatest grain N concentration (mean 15.1 g kg−1). However, recent hybrids resulted in medium prolificacy (mean 1.11 ears plant−1) with the highest yield per unit area (mean 910 g m−2), but with the lowest grain N concentration (mean 13.6 g kg−1). The different pattern of grain N concentration among hybrids coupled with similar NHI (mean 0.80) led to the lowest NIE of the most prolific hybrids (mean 55 g yield g N−1) relative to the less prolific ones (mean 60 g yield g N−1). Variations in NIE among genotypes and plant densities were negatively influenced by grain N concentration under N- and under N+ only when prolificacy = 1. Under N+ with prolificacy > 1, NIE variations were positively determined by NHI. For all genotypes, higher yield per plant (mean 30 %) and total N uptake (mean 25 %) were recorded for the prolific plants, reflected in the greater absolute NIE (mean 5 %). For the oldest hybrid differences between prolific and non-prolific plants in NIE (mean 46.8 vs 41.8 g yield g N-1) were greater than those recorded for the other genotypes due to the higher impact of prolificacy on yield per plant (mean 51 %) than on total N uptake (mean 26 %). Over time, improvements in NIE primarily occurred from greater yield of the apical ear. Overall, the expression of prolificacy appears to be an adequate strategy to stabilize maize production in response to improvements of environmental conditions, specially addressed by low plant density and high N supply.

The combined and interactive effects of orientation, strain amplitude, cycle number, stacking fault energy and hydrogen doping on microstructure evolution of polycrystalline high-manganese steels under low-cycle fatigue

We studied the combined and interactive effects of crystallographic orientation, strain amplitude, cycle number, stacking fault energy (SFE) and hydrogen doping on the microstructure evolution of polycrystalline high-manganese steels (HMnSs) under low-cycle fatigue (LCF). An integrated experimental approach combining digital image correlation (DIC), electron backscatter diffraction (EBSD) and electron channelling contrast imaging (ECCI) at interrupted cycles was performed in the same region of interest on the bulk shear samples, which enables us to systematically compare the dislocation patterns of grains with defined loading conditions at a much larger field of view and less artefacts compared to transmission electron microscopy (TEM). We found that Taylor factor (M) works well with describing the effect of crystallographic orientation, which was further proved by the crystal plasticity finite element method (CPFEM). In detail, grains with a medium M value (3.3–3.9) tend to form more complex dislocation pattern, which is defined as sensitive value. Generally, increasing strain amplitude and cycle number both promote the evolution of dislocation pattern while their efficiencies depend strongly on grain orientation. The promotion effect of SFE on dislocation evolution becomes obvious at larger strain amplitudes (>0.4%) and non-sensitive M value. Hydrogen can strongly assist the formation of ε-martensite and reduce its critical resolved shear stress (CRSS), while it retards the evolution of dislocation pattern. The number of activated martensite variants in individual grain can be well predicted by its M value. With increasing strain amplitude, the fraction of ε-martensite increases in a manner of thinner but denser plates.

Investigation of corrosion performance of aluminum and zinc alloys in three acidic media

The consequences of corrosion are many and varied, and their effects of these on the safe, reliable and efficient operation of equipment or structures are often more serious than a simple loss of metal mass. This research investigates the corrosion performance of two nonferrous metals in three acidic media, namely sulfuric acid (98% volume of H2SO4), hydrochloric acid (75% volume of HCl), and trioxonitrate (V) acid (75% volume of HNO3). The corrosion rate is determined by the weight loss method, and the characterization of metallic samples is obtained by scanning electron microscope (SEM). The SEM shows the cracking pattern of grains indicating surface erosion due to the corrosion effects which are more depicted on the zinc than aluminum samples. It is shown that the solution of H2SO4 has the highest impact on the corrosion rates of metallic samples, whereas the least effect is observed on the solution of HNO3. It is observed that Zn alloy sample in 3 M H2SO4 records the highest corrosion rate of 138.64 mm/year, while the aluminum alloy sample has the lowest rate of 24.661 mm/year after 72 hours of exposures in the acid. The corrosion rates of the samples decrease as the exposure time increases. The weight loss intensity increases with exposure time for Al samples and varies for Zn sample in acidic media. In conclusion, the higher the acid molarity, the shorter the exposure time and the higher the corrosion rates for both zinc and aluminum alloy samples.

One-step preparation of CaO-doped partially stabilized zirconia from fused zirconia

Partially stabilized zirconia (PSZ) replaces the widespread applications of full stabilized zirconia (FSZ) on ceramics materials and refractories materials, attributed to its excellent properties including small coefficient of thermal expansion, low thermal conductivity and good thermal shock resistance. In this work, CaO-doped partially stabilized zirconia (CaO-PSZ) was optimizedly prepared from fused zirconia through conventional roasting. Meanwhile, the effects of roasting temperature and duration time on stability properties were explored to determine the stability parameters of the prepared CaO-PSZ. Results indicated that the zirconia stability rate synchronously improved with the decrease of roasting temperature and duration time, which was attributed to that the martensitic transformation of fused zirconia with volume change plays a toughening effect, further rendering the change of zirconia stability properties. XRD patterns verified the martensitic transformation, representing by cubic ZrO2 phase (c-ZrO2) in raw fused zirconia was partially transformed into monoclinic ZrO2 phase (m-ZrO2) at 1450 °C for 4 h. Moreover, the phase transition law of fused zirconia was revealed through SEM and EDAX characterization for the raw fused zirconia and the prepared CaO-PSZ. SEM patterns showed acicular patterns of grains and round fine particles clustered at grain boundaries, indicating that CaO stabilizer precipitated on grain boundaries and rendered the crystal structure enhanced, which the result was consistent with EDAX analysis. This work can lay a significant foundation for applications of microwave heating on the preparation of partially stabilized zirconia (PSZ) from fused zirconia.

Green manufacturing with a bionic surface structured grinding wheel-specific energy analysis

Grinding has lower green degree than other cutting methods, for which higher specific grinding energy is one of the important reasons. For reducing specific grinding energy to obtain a green process in grinding, a bionic structured surface inspired by phyllotaxis theory was developed in this paper. To verify its performance, some contrast experiments to measure specific grinding energy were conducted. The experiments of grinding surface roughness were also conducted to avoid pursuing lower specific grinding energy alone. The results showed that the bionic surface structured grinding wheel had smaller specific grinding energy with better grinding surface roughness due to the bionic pattern of grains. This research will provide a new mean for the development and application of green manufacturing technology.

Evaluating the impacts of socio-economic factors on regional grain virtual water flows in China using a structural equation modeling approach

Changes in the patterns of regional economic and social development will affect regional agricultural and industrial structures, thereby affecting grain cultivation patterns. Imbalances between the grain supply and demand will trigger interregional grain flow. Grain is a water-intensive product, and virtual water embedded in grain products flows between regions, which will affect the utilization and distribution of regional water resources. This study evaluated the impacts of socio-economic factors on regional grain virtual water flows by using the partial least squares structural equation model (PLS-SEM). Results show that grain production centers in China are being transferred to the northern regions due to the evolution of economic patterns over the past 30 years. Driven by the imbalance between the regional grain supply and demand, the virtual water flow patterns of grain shows a tendency to flow from the northern and western provinces to the southern and eastern provinces. Results of structural equation modeling show that there is a significant causal structure between socio-economic factors and grain virtual water flows. The study indicates that the regional socio-economic pattern and its evolution will affect the grain virtual flow patterns. Consequently, virtual water flows will exert great pressure on water resources in the virtual water export areas, and the expansion of the virtual water export will increase the difficulty of regional water resources systems in supporting regional social and economic sustainable development and grain production, thus posing a potential challenge to China's water resources and grain security.

Grain Filling Variation in Winter Wheat, Barley and Triticale in Pannonian Environments

Knowledge about the comparative development and grain filling of winter cereals under different environmental conditions is important for stable and high yielding crop production. The objective of this work was to compare patterns of grain filling in bread wheat, barley and triticale grown in the Pannonian region, as well as to investigate relationships among grain filling parameters, time to anthesis and grain yield. The trials with 12 winter cereal genotypes were carried out in four successive seasons at the location Novi Sad, Serbia. Results of this study showed that all studied grain filling parameters were significantly influenced by species, cultivar, growing season, and species by growing season interaction. Longer duration of grain filling period and period to maximum grain filling were observed in triticale and wheat cultivars compared with six and two-rowed barley. Two-rowed barley cultivars had a higher grain filling rate than other cultivars. Furthermore, a negative association between time to anthesis and grain yield indicates that cultivars with the long pre-anthesis period are not recommended for the agro-ecological conditions of the Pannonian plain. Generally, medium early cultivars of small grain cereals had the highest grain weight within species and spike type, suggesting that medium early cultivars have a balanced ratio of pre-anthesis and grain filling period. High values of final grain weight in different growing seasons indicate that weather conditions in the Pannonian plain are mainly suitable for grain growth.

Agroecological and agroeconomic aspects of the grain and grain legumes (pulses) yield dynamic within the Dnipropetrovsk region (period 1966–2016)

This paper reveals the spatial and temporal patterns of grain and leguminous crops yield dynamics in Dnipropetrovsk region and evaluates the role of agro-environmental and agro-economic factors in their formation. Crop data were obtained from the State Statistics Service of Ukraine. The data of the grain and grain legumes (pulses) yield during 1966–2016 on average per year in the administrative districts of Dnipropetrovsk region was analysed. The obtained data indicate that average yields of cereals and leguminous crops within Dnipropetrovsk region varies from 24.3 to 33.4 CWT/ha. The smallest interannual variability in yield is typical for Vasylkivskyi district (CV = 9.9%), and the largest is typical for Yurivskyi district (CV = 27.7%). As a result of the principal component analysis of the cereals and leguminous crops yields variability, three principal components were extracted which together explain 81.2% of the overall yield variability. Principal component 1 explains 69.4% of the total variability. It indicates the total synchronous yields variation within the area investigated as all examined variables have high loading values on principal component 1. The administrative districts that form a belt located in the direction from the north east to the south west of the region have the most coordinated variance, which is reflected by principal component 1. Principal component 2 explains 6.8% of the yield variability. This principal component is sensitive to opposite yield dynamics of central and south-western districts on the one hand and the eastern and northern districts – on the other. Principal component 3 explains 4.9% of the yield variability. This principal component reveals the opposite dynamics of productivity of the central districts on the one hand and the northern and south-eastern districts on the other. The cluster analysis of administrative districts was conducted based on the dynamics of the yield of grain and leguminous as a result of which four clusters were identified. The clusters are geographically defined administrative districts, together forming spatially connected areas. The similar temporal yield dynamics of grain and leguminous crops as a result of interaction between endogenous and exogenous ecological factors is the main principle for revealling such ecologically homogeneous territories. Spatial distribution of principal components indicates a continual pattern, but their overlapping allows one to extract spatially discrete units, which we identified as agroecological zones. Each zone is characterized by a certain character and dynamics of production capacity and has an invariant pattern of response to varying climatic, environmental, and agroeconomic factors.

Impacts of incorporating dominant crop rotation patterns as primary land use change on hydrologic model performance

Abstract Crop rotation is a commonly used management practice in the central U.S. whereby different agricultural crops are grown on a farm field in successive years to help maintain the productive capacity of the soil. Understanding hydrologic responses to crop rotation is critical for developing appropriate crop rotation strategies for sustainable water resources management. These responses are not well understood due to limited availability of multi-year, crop-specific land use-land cover data. The study focuses on the Smoky Hill River watershed in west-central Kansas, a typical agro-ecosystem watershed in the Central Great Plains of the U.S. A multi-year land use dataset developed for the state of Kansas was used to identify 3-year crop rotation patterns in the watershed for three different periods (2006–08, 2008–10, 2010–12). Out of 276 unique rotations, 21 rotations were found to be dominant, with rotation patterns of grain sorghum-fallow-winter wheat (G-F-W), winter wheat-winter wheat-fallow (W-W-F), and continuous winter wheat (W-W-W) occupying more than 81% of the cropland in each rotation period. From 2006 to 2012, the coverage of grain sorghum increased by 26% and corn by 305%, while winter wheat decreased by 20%. Three 11-year simulation scenarios based on three 3-year crop rotation patterns were implemented in the SWAT model and separately calibrated for streamflow at two gauge sites. The SWAT model produced good calibration statistics for the periods corresponding to the applied crop rotations, while the statistics tended to decrease for other periods, with Nash-Sutcliffe Efficiency coefficient becoming unsatisfactory for periods of six to eight years outside of the calibration period. Applying a different number of dominant crop rotations to the SWAT model, it was found that the number can be reduced down to the five most dominant without significant loss in model performance. While the optimum number of crop rotations must be evaluated for each agricultural watershed, this finding provides valuable information for watershed model development and calibration, which can help to avoid issues of over-parameterization and equifinality.