Thông tin tài liệu
Abstract Under the global change, analyzing and interpreting spatiotemporal variability in crop yield and soil characteristics are keystones of sustainable agricultural production, especially site-specific farming This study focuses on maize, one of the most important crops for food, feed, and biomass Management practices have a significant influence on maize growth and the environment As a shallow rooter, maize benefits from uniform growth conditions in mechanically prepared topsoil by plowing A no-tillage cropping system can reduce soil compaction and offer the possibility of soil, water, and climate protection future environmental quality Irrigation, as well as crop rotation, may also highly influence the maize yield as well as soil health Thus, this study explored the influences of the three major land-use management factors – soil tillage, irrigation, and crop rotation – on maize biomass yield and soil characteristics throughout nine years of their applications from 2008 – 2016 from an experimental field study in Müncheberg, Germany The treatments were tillage (no-tillage, plow tillage), irrigation (rainfed, irrigated), and crop rotation (continuous maize, 4-year crop rotation) The objectives of this thesis were 1) to explore the influences of soil tillage, irrigation, and crop rotation methods on maize above-ground biomass yield and its spatiotemporal variability; 2) to analyze spatiotemporal variability in soil characteristics under impacts of different land-use management methods; 3) to predict biomass yield using UAV-based imagery and assess its spatial variability based on the predicted biomass yield map Firstly, I analyzed the development of maize above ground biomass yield through years The generalized linear model showed that tillage, irrigation, and crop rotation jointly explained approximately 35% of the total variance Tillage significantly affected maize biomass yield from the fourth year In contrast, irrigation immediately positively influenced maize biomass yield in 2008, and crop rotation was in 2011 In general, irrigation had the most relative importance as a management factor compared to the extent of tillage and crop rotation Crop rotation with legumes increased soil nitrogen and carbon content and led to a higher yield than continuous maize 11.1 dt ha-1 y-1 on average The significant effect of crop rotation on the yield of the following crop (maize) continued after two cycles of a 4-year crop rotation A considerable influence of the 2-way interactions between rotation, tillage, and irrigation was only in extreme drought years Therefore, it can conclude that (i) the negative influence of notillage becomes noticeable after three years, leading to significantly lower yield compared to plow tillage; (ii) under the sandy soil and dry conditions, irrigation significantly increases yields - iv - and is the most critical factor compared to tillage and crop rotation; (iii) crop rotation significantly increases and maintains maize yield under both plowed and irrigated conditions Secondly, I analyzed the effects of treatments on total nitrogen (Nt), phosphorus (P), potassium (K), and magnesium (Mg) contents Soil samples were taken four years after the establishment of the experiment in April 2011 (short term) and four years later in 2015 (long term) at to15 cm, 15 to 30 cm, and 30 to 60 cm soil layers Tillage, irrigation, and rotation significantly influenced Nt, P, K, and Mg, resulting in space changes at all three studied soil layers and between the short and long term Only K content was significantly different among treatments in all three tested soil layers in short and long periods The tillage:rotation interaction significantly influenced all tested soil chemical characteristics in the 15 cm soil surface, while other interactions did not In the long run, the contents of Nt and P slightly decreased in the uppermost but increased in lower soil layers The relative importance of tillage, irrigation, and rotation influencing the tested soil macronutrients changed in space at to 60 cm soil depth and time, between the 1st and 2nd rotation cycle Among the treatment factors, tillage became the most crucial factor for the tested soil macronutrients within the top 30 cm soil depth in the long term Thirdly, I used two types of UAV-based imagery, visible (RGB) and multispectral images, in 2015 for estimating above-ground biomass yield and then mapping its predicted yield to see the spatial variability of maize biomass yield across the trial field The findings explored new knowledge that (1) the BMA approach improved the accuracy of maize yield prediction using UAV imagery; (2) the effectiveness of UAV-based RGB (R2 = 0.85) was lower than multispectral imagery (R2 = 0.96) in forecasting maize biomass; (3) best predictive model algorithms based Bayesian inference proved the capability to determine appropriate vegetation indices for predicting maize biomass As a result, it provides a capability to quickly assess the spatiotemporal variability in maize biomass yield across the field that can easily apply proper and precise fertilization, liming, irrigation, and other land-use management methods With appropriate and enough available data, the findings concluded that it is easy to track spatiotemporal variability in above-ground biomass yield across the field with UAV-based remote sensing In conclusion, this dissertation found scientific evidence that under poor sandy soil and drought conditions, different methods of soil tillage, irrigation, and crop rotation led to the significant spatiotemporal variability in maize biomass yield and soil characteristics -v- ... that under poor sandy soil and drought conditions, different methods of soil tillage, irrigation, and crop rotation led to the significant spatiotemporal variability in maize biomass yield and soil. .. types of UAV-based imagery, visible (RGB) and multispectral images, in 2015 for estimating above-ground biomass yield and then mapping its predicted yield to see the spatial variability of maize biomass. .. quickly assess the spatiotemporal variability in maize biomass yield across the field that can easily apply proper and precise fertilization, liming, irrigation, and other land-use management methods
Ngày đăng: 29/10/2022, 03:34
Xem thêm:
