Abstract
The yield of grain crops and its predictability largely depends on the intra-field heterogeneity of landscape conditions. We used the example of steppe agricultural landscapes in the Akmola region to solve the following objectives: 1) to evaluate the informative value of NDVI for assessing yield depending on hydrothermal conditions; 2) to determine the effect of intra-field patchiness on NDVI values and yield; 3) to determine the dependence of intra-field variation of phytomass on the tract and facies structure and hydrothermal conditions. We used data on wheat and barley yields and intra-field NDVI variability in 80 field plots in 2009‒2013, data on the tract and facies structure, and hydrothermal parameters. We studied the relationships between spatial and temporal variability of phytomass, landscape and hydrothermal factors by means of correlation and variance analysis. It was established that NDVI was only partially informative for direct assessment of grain yield. The index values for July dates better reflect the yield than in June and August. The hypothesis that NDVI patchiness in the field area depends on the cultivated crop was not confirmed. The yield in fields with complex facies structure is usually lower than in homogeneous fields. In dry years, the intra-field variation of phytomass is less pronounced than in wet years. The proximity to the hill is a significant factor that increases the spatial variability of phytomass due to the additional introduction of moisture and sediment along the rills. High facies patchiness either reduces yield or increases its temporal variability and reduces predictability.
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Claims 7
Claim · model-written summary
NDVI was only partly informative for grain yield assessment.
Verbatim
e0“It was established that NDVI was only partially informative for direct assessment of grain yield.”
e1“grain crops”
Claim · model-written summary
July NDVI reflected yield better than June or August NDVI.
Verbatim
e0“The index values for July dates better reflect the yield than in June and August.”
e1“grain crops”
Claim · model-written summary
NDVI patchiness did not depend on the crop cultivated.
Verbatim
e0“The hypothesis that NDVI patchiness in the field area depends on the cultivated crop was not confirmed.”
e1“grain crops”
Claim · model-written summary
Fields with complex facies structure usually had lower yields than homogeneous fields.
Verbatim
e0“The yield in fields with complex facies structure is usually lower than in homogeneous fields.”
e1“grain crops”
Claim · model-written summary
Within-field phytomass varied less in dry than wet years.
Verbatim
e0“In dry years, the intra-field variation of phytomass is less pronounced than in wet years.”
e1“grain crops”
Claim · model-written summary
Proximity to hills increased spatial phytomass variability.
Verbatim
e0“The proximity to the hill is a significant factor that increases the spatial variability of phytomass due to the additional introduction of moisture and sediment along the rills.”
e1“grain crops”
Claim · model-written summary
High facies patchiness reduced yield or increased its temporal variability and reduced predictability.
Verbatim
e0“High facies patchiness either reduces yield or increases its temporal variability and reduces predictability.”
e1“grain crops”