Using remote sensing technologies to enhance resource conservation and agricultural productivity in underutilized lands of South Asia

Satisfying the food demands of an ever-increasing population, preserving the natural resource base, and improving livelihoods are major challenges for South Asia. A large area of land in the Middle and Lower Gangetic Plains of South Asia remains either uncultivated or underused following the rice harvest in the kharif (wet) season. The area includes “rice-fallow,” estimated at 6.7 million ha, flood-prone riversides (“diara lands,” 2.4 million ha), waterlogged areas (4.9 million ha), and salt-affected soils (2.3 million ha). Bringing these lands under production could substantially improve the food supply and enhance livelihoods in the region. This paper describes a methodological case study that targeted resource-conserving technologies in underused lands of the Ballia District of eastern Uttar Pradesh (India) using multispectral remote-sensing images. Classification of temporal satellite data IRS-P6 in combination with Spot VGT 2 permitted the identification of all major categories of underused land during the post-rainy rabi/winter season, with an average accuracy of 89%. Based on three-year averages of field demonstrations, farmers gained an additional income of $63 ha⁻¹ by introducing raised beds in salt-affected soils; $140 and $800 ha⁻¹ by introducing deepwater rice varieties (monsoon) and boro rice (winter) in waterlogged areas; and $581 ha⁻¹ by introducing zero-till lentil (winter) in rain-fed fallow lowland. Timely wheat planting through zero-tillage implies an additional income of $147 ha⁻¹ and could increase wheat production by 35,000-65,000 tons in the district. The methodologies and technologies suggested in the study are applicable to more than 15 million ha of underutilized lands of the Indo-Gangetic Plains of South Asia. If the technologies are precisely applied, they can result in more than 3000 million US $ of additional income every year to these poverty prone areas.     

水稻群体动态预测与栽培决策

本文以作物计算机模拟技术为基础，根据天气，土壤，苗情，模拟预测水稻群体的发育群、茎蘖消长、叶面积动态、光合生产与产量形成。     

水稻不同生长期稻田能量收支、CO2通量模拟研究

利用国家自然科学基金重大项目“长江三角洲低层大气物理化学过程与生态系统的相互作用”野外观测资料，将1999年常熟稻田水稻四个不同生长期（插秧、拔节、抽穗和成熟）的太阳辐射、水汽压、气温和水平风速及降水作为简化生物圈（SiB2）模式的5个强迫变量，在合理设计模式参数的前提下，分别模拟了上述四个阶段的能量收支、CO₂通量。模拟结果表明:在水稻不同生长阶段的感热、潜热和下垫面热通量占净辐射的比例不同；CO₂通量的模拟结果与1996年国际稻田试验结果相似。该研究为利用自动气象站网的资料估计各站能量收支、CO₂通量、土壤水分平衡、以及土壤温度廓线提供了新证据。     

江西水稻产量波动的成因分析及对策

以江西历年气象观测资料为基础，分析了气候务件对江西水稻生产的影响，并从气象的角度。提出了提高江西粮食综合生产能力及保障粮食安全的建议。     

水稻种植面积估计的运行化遥感方法

该文提出了用高分子辨率遥感数据提取水稻种值面积本底数据和用可靠低廉的ＮＯＡＡＡＶＨＲＲ数据估计水稻种植面积变化趋方法。该方法具有运行化的特点，成功地应用于１９９４年度湖北省早稻种植面积估算。     

Stress on tropical karst cultivated with wet rice: Bohol, Philippines

Wet rice cultivation represents one of the most intensive uses of tropical karst. Under wet field conditions karstlands can be highly resilient, but nevertheless vulnerable to change. The karst environment in this study has been cultivated for at least five centuries. However, the post-World War II era has fostered a host of pressures that have altered the local ecology. Resulting stress in the irrigation systems and society threaten the maintenance of this viable karst-based agricultural economy.     

水稻叶片不同光谱形式反演叶绿素含量的对比分析研究

通过对常优1号和武粳15两个品种水稻叶片的反射率R、lg(1/R)、反射率一阶微分（FD）和反射率归一化（BN）等光谱形式的测量和计算，分析了叶片光谱不同变化形式与叶绿素含量的相关关系，建立了统计方程，并进行了比较与评价，同时，对反演方程的最佳波段选择进行了探讨。结果表明，叶绿素含量与反射率一阶微分光谱方程的相关性最强，而采用lg(1/R)的光谱形式能够提高遥感反演叶绿素含量的效果。经验证，两个水稻品种叶绿素含量的模拟值与实测值的复相关系数R2分别达到0.641和0. 818。     

Advanced vegetation indices for sensing paddy growth via hyperspectral measurements

In this study, field-based spectroradiometer measurements were carried out in 72 plots with eight rice varieties along with three nitrogen applications. The critical wavelengths for the studied rice varieties at which the effects of nitrogen applications on spectral reflectance response were found significant, are ρ₅₅₀, ρ₅₆₀, ρ₆₅₅, ρ₇₅₀, ρ₇₅₅, ρ₇₈₀, ρ₈₁₀, ρ₈₄₀, ρ₉₀₀, ρ₉₂₀, ρ₁₀₀₀, ρ₁₀₁₀, ρ₁₀₂₀. Using the critical wavelengths, three derived vegetation indices were compared with established indices (VI and GRI) sensitive to nitrogen. VI₁ and VI₂ were efficiently able to discriminate the level of nitrogen treatments for most of the rice genotypes whereas VI and GRI were unable to find significant difference in nitrogen treatments for rice genotypes except two. Furthermore, nitrogen difference plots exhibited that the paddy crop growth has started earlier with N₃ (150 kg/ha) than N₂ (100 kg/ha) application. Quantitative analysis of rice genotypes revealed that VI₂ can be applied functionally for the assessment of nitrogen stress in rice agriculture system.     

浮体栽培陆生高等植物对农业富营养化水体的净化作用

Experiments on surface aquaponics were carried out in simulatedly-eutrophicated cement ponds with the concentrations ofkjeldahl nitrogen (KN) 2.084 mg·l^-1 and TP 0.248 mg·l^-1 and without any interference from natural environment factors. On the surface of ponds rice was planted on floating-beds without soil for the purpose of collecting nutrients (N & P) from water by absorption and adsorption of rice roots. The results show that the design is not only feasible but also very effective. When the coverage of rice on floating-beds were 20%, 40% and 60%, respectively with the water depth of about 1.4 m, the removal rates of KN in water reached 29.0%, 49.8% and 58.7%, respectively and those of TP 32.1%, 42.0% and 49.1%, respectively during the test period of 84 days from tillering to maturing of rice. Other main parameters of water quality were greatly improved. The results provided a scientific basis for surface aquaponics engineering to purify eutrophicated water bodies by planting terrestrial higher plants on floating-beds.     

SAR数据在南方水稻分布图快速更新中的应用方法研究

研究表明,SAR数据对水稻识别和作物长势监测很有潜力。本文研究了在GIS的支持下,用SAR数据对南方水稻分布图进行快速更新的方法。首先,对多时相的SAR数据进行GammapMap滤波、几何精纠正和辐射干扰校正等处理;然后,采用最大似然法进行有监分类,获得水稻分布图;最后,对新、旧水稻分布图作标识码的Overlay处理,即可将水稻分布图更新。结果表明,该方法具有可操作性强,分类、制图精度高的特点。