Factors affecting the growth of Pennisetum purpureum in the wet tropics. I. Short-term growth and regrowth

1980 ◽  
Vol 31 (5) ◽  
pp. 899 ◽  
Author(s):  
R Ferraris ◽  
DF Sinclair
Keyword(s):  
Soil Moisture ◽  
Stem Elongation ◽  
Experimental Period ◽  
Elongation Growth ◽  
Pennisetum Purpureum ◽  
Moisture Regime ◽  
Short Term ◽  
Moisture Percentage ◽  
Wet Tropics ◽  
Tiller Density

Six plantings of elephant grass (Pennisetum purpureurn) were made at 2-monthly intervals in the wet tropics of north Queensland. Each crop was sampled for yield at monthly intervals. After 6 months' growth each crop was ratooned for a further 6 months' growth, with yield samples again being taken at monthly intervals. As well, stem elongation growth was measured twice weekly, together with various climatic parameters and soil moisture to 90 cm. Regrowths after each monthly harvest were sampled 1 month after cutting. Short-term growth, measured as elongation growth and averaged for the whole experimental period, was found to have a significant parabolic relationship with crop age and available soil moisture percentage, but not with average temperature or evaporation. Regrowth yields were found to be linearly and positively correlated with tiller density prior to ratooning and regrowth tiller density, with average regrowth temperature or regrowth degree days but linearly and negatively correlated with moisture regime, whether expressed as average parent-crop soil moisture prior to harvest, average regrowth soil moisture percentage or the summation of stress-free days. It was concluded that environmental limitations to growth in this environment, though relatively short lived, were significant in reducing long-term yields. Growth, however, was possible at all times.

Soil Moisture Regime Changes in Tephra-Mulched Soils

2002 ◽  
Vol 66 (1) ◽  
pp. 202 ◽  
Author(s):  
M. Tejedor ◽  
C. C. Jiménez ◽  
F. Díaz
Keyword(s):  
Soil Moisture ◽  
Moisture Regime ◽  
Regime Changes ◽  
Soil Moisture Regime

Populations of endogonaceous fungi at two locations in central Iowa

1982 ◽  
Vol 60 (12) ◽  
pp. 2518-2529 ◽  
Author(s):  
Christopher Walker ◽  
Carl W. Mize ◽  
Harold S. McNabb Jr.
Keyword(s):  
Soil Moisture ◽  
Growing Season ◽  
Experimental Period ◽  
Spore Production ◽  
Moisture Level ◽  
Small Samples ◽  
Soil Moisture Level ◽  
Hybrid Poplars ◽  
Herbicide Treatment

Two different sites in central Iowa were planted with hybrid poplars and subsequently sampled over a growing season for spores of endogonaceous fungi. At one of the sites, the effects of plowing and herbicide treatment on spore numbers also were examined. Ten species of fungi in the genera Acaulospora, Gigaspora, and Glomus were recorded at the first site. The second location yielded 12 species from the same genera. In both sites, the distribution of spores was highly variable. The poplars rarely became endomycorrhizal and had no effect on spore populations during the experimental period. Changes in spore populations were correlated with soil-moisture level. Evidence was found for some depression of spore production caused by plowing and herbicide treatment. The conclusion was drawn that small samples with but few replicates may not adequately represent populations of endogonaceous spores.

The soil moisture regime under native grassland

Geoderma ◽  
1975 ◽  
Vol 14 (3) ◽  
pp. 207-221 ◽  
Author(s):  
E.De Jong ◽  
K.B. MacDonald
Keyword(s):  
Soil Moisture ◽  
Moisture Regime ◽  
Soil Moisture Regime ◽  
Native Grassland

scholarly journals Interactive effects of ambient ozone and climate measured on growth of mature loblolly pine trees

1996 ◽  
Vol 26 (4) ◽  
pp. 670-681 ◽  
Author(s):  
S.B. McLaughlin ◽  
D.J. Downing
Keyword(s):  
Soil Moisture ◽  
Loblolly Pine ◽  
Moisture Stress ◽  
Growth Patterns ◽  
Forest Growth ◽  
Interactive Effects ◽  
Forest Trees ◽  
Short Term ◽  
Data Set ◽  
Ambient Ozone

Seasonal growth patterns of mature loblolly pine (Pinustaeda L.) trees over the interval 1988–1993 have been analyzed to evaluate the effects of ambient ozone on growth of large forest trees. Patterns of stem expansion and contraction of 34 trees were examined using serial measurements with sensitive dendrometer band systems. Study sites, located in eastern Tennessee, varied significantly in soil moisture, soil fertility, and stand density. Levels of ozone, rainfall, and temperature varied widely over the 6-year study interval. Regression analysis identified statistically significant influences of ozone on stem growth patterns, with responses differing widely among trees and across years. Ozone interacted with both soil moisture stress and high temperatures, explaining 63% of the high frequency, climatic variance in stem expansion identified by stepwise regression of the 5-year data set. Observed responses to ozone were rapid, typically occurring within 1–3 days of exposure to ozone at ≥40 ppb and were significantly amplified by low soil moisture and high air temperatures. Both short-term responses, apparently tied to ozone-induced increases in whole-tree water stress, and longer term cumulative responses were identified. These data indicate that relatively low levels of ambient ozone can significantly reduce growth of mature forest trees and that interactions between ambient ozone and climate are likely to be important modifiers of future forest growth and function. Additional studies of mechanisms of short-term response and interspecies comparisons are clearly needed.

A soil moisture meter. Depending on the “capillary pull” of the soil. With illustrations of its use in fallow land, grass orchard, and irrigated orchards

1935 ◽  
Vol 25 (3) ◽  
pp. 326-343 ◽  
Author(s):  
W. S. Rogers
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Continuous Measurement ◽  
Fallow Land ◽  
Soil Particles ◽  
Moisture Meter ◽  
Two Factors ◽  
Moisture Percentage ◽  
Mercury Manometer

1. A soil moisture meter which gives direct and continuous measurement of the soil moisture content is described. The instrument consists of a special porous pot filled with water, connected by a tube to a mercury manometer. The pot is buried in the soil, whose capillary pull causes the mercury to rise. The height to which the mercury rises depends on the amount of moisture in the soil, and also on the size of soil particles and the degree of compactness of the soil. (The last two factors remain constant for an instrument in one position.)2. To read actual moisture percentage each instrument has to be calibrated for the soil in which it is placed. Once this is done, all sampling and weighing is eliminated.

scholarly journals An Indirect Approach Based on Long Short-Term Memory Networks to Estimate Groundwater Table Depth Anomalies Across Europe With an Application for Drought Analysis

2021 ◽  
Vol 3 ◽  
Author(s):  
Yueling Ma ◽  
Carsten Montzka ◽  
Bagher Bayat ◽  
Stefan Kollet
Keyword(s):  
Soil Moisture ◽  
Indirect Method ◽  
Short Term Memory ◽  
Groundwater Table ◽  
Short Term ◽  
Data Set ◽  
Term Memory ◽  
Continental Scale ◽  
Groundwater Table Depth ◽  
Long Short Term Memory

The lack of high-quality continental-scale groundwater table depth observations necessitates developing an indirect method to produce reliable estimation for water table depth anomalies (wtda) over Europe to facilitate European groundwater management under drought conditions. Long Short-Term Memory (LSTM) networks are a deep learning technology to exploit long-short-term dependencies in the input-output relationship, which have been observed in the response of groundwater dynamics to atmospheric and land surface processes. Here, we introduced different input variables including precipitation anomalies (pra), which is the most common proxy of wtda, for the networks to arrive at improved wtda estimates at individual pixels over Europe in various experiments. All input and target data involved in this study were obtained from the simulated TSMP-G2A data set. We performed wavelet coherence analysis to gain a comprehensive understanding of the contributions of different input variable combinations to wtda estimates. Based on the different experiments, we derived an indirect method utilizing LSTM networks with pra and soil moisture anomaly (θa) as input, which achieved the optimal network performance. The regional medians of test R2 scores and RMSEs obtained by the method in the areas with wtd ≤ 3.0 m were 76–95% and 0.17–0.30, respectively, constituting a 20–66% increase in median R2 and a 0.19–0.30 decrease in median RMSEs compared to the LSTM networks only with pra as input. Our results show that introducing θa significantly improved the performance of the trained networks to predict wtda, indicating the substantial contribution of θa to explain groundwater anomalies. Also, the European wtda map reproduced by the method had good agreement with that derived from the TSMP-G2A data set with respect to drought severity, successfully detecting ~41% of strong drought events (wtda ≥ 1.5) and ~29% of extreme drought events (wtda ≥ 2) in August 2015. The study emphasizes the importance to combine soil moisture information with precipitation information in quantifying or predicting groundwater anomalies. In the future, the indirect method derived in this study can be transferred to real-time monitoring of groundwater drought at the continental scale using remotely sensed soil moisture and precipitation observations or respective information from weather prediction models.

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