scholarly journals Multiyear analysis of the dependency of the planting date on rainfall and soil moisture in paddy fields in Cambodia, 2003–2019

2021 ◽  
Author(s):  
Kumiko Tsujimoto ◽  
Kotaro Ono ◽  
Tetsu Ohta ◽  
Koemorn Chea ◽  
E-Nieng Muth ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Remote Sensing Data ◽  
Planting Date ◽  
Paddy Fields ◽  
Planting Dates ◽  
Phnom Penh ◽  
Tonle Sap Lake ◽  
Tonle Sap ◽  
Dry Spells ◽  
Western Side

AbstractThe dependencies of the planting date on rainfall and soil moisture in paddy fields in Cambodia were analyzed to quantify farmers’ empirical knowledge regarding their decision of the planting date. Remote sensing data from multiple satellites covering the 2003–2019 period were analyzed. The planting dates in rain-fed paddies ranged from April to August, with large spatial variations and year-to-year fluctuations. In years when planting was suppressed in April and May, planting was extensively enhanced in June and August compared to normal years, and vice versa. Over the northeastern side of Tonle Sap Lake and south of Phnom Penh city, the areas planted in April and May were found to have positive correlations with rainfall and soil moisture, suggesting that wetter-than-average conditions encouraged farmers to plant earlier in the season. In contrast, this relationship was unclear on the western side of Tonle Sap Lake, where the rainfall amounts were larger throughout the year than in other areas in Cambodia. In this region, the relationship between the planting area and soil water availability was either unclear or was even slightly negative from June to August. Since more frequent dry spells have been detected after the onset of the rainy season in recent years, further studies and disseminations of potential changes in dry spells are important for the agronomic adaptation of planting dates under climate change.

Effects of Planting Date and Mulching on Cowpea in Sierra Leone

1981 ◽  
Vol 17 (1) ◽  
pp. 25-31 ◽  
Author(s):  
C. S. Kamara
Keyword(s):  
Soil Moisture ◽  
Sierra Leone ◽  
Plant Height ◽  
Seed Yield ◽  
Middle Part ◽  
Planting Date ◽  
Growth And Yield ◽  
Planting Dates ◽  
Beneficial Effects ◽  
Pod Number

SUMMARYThe effects of date of planting and soil mulching on cowpea growth and yield were investigated for three years during the middle part of the minor season in Sierra Leone. Mulching at 8 tons/ha conserved more soil moisture than other mulch rates, with greatest difference in the top 15 cm of soil, especially during drier periods. Plant height, pod number and seed yield of cowpea planted in September were significantly greater than from other planting dates whether mulch was applied or not. The beneficial effects of mulching at 8 tons/ha on cowpea growth and yield were more dramatic when the crop received an average weekly rainfall of 100 mm before 50% flowering.

Time of Planting, Rainfall and Soil Moisture Effects on Cowpea in Sierra Leone

1979 ◽  
Vol 15 (4) ◽  
pp. 315-320 ◽  
Author(s):  
C. S. Kamara ◽  
W. Godfrey-Sam-Aggrey
Keyword(s):  
Soil Moisture ◽  
Grain Yield ◽  
Sierra Leone ◽  
Planting Date ◽  
Growth Stages ◽  
Total Rainfall ◽  
Planting Dates ◽  
Grain Yields ◽  
Moisture Effects ◽  
Different Growth Stages

SUMMARYAn experiment was conducted during the minor season in Sierra Leone to determine the optimum planting date for a photo-insensitive cowpea cultivar and study the relations between total rainfall and soil moisture available at different growth stages. Cowpeas planted in early September produced the tallest plants and higher grain yields than from other planting dates, since they benefited from 90% of the season's rainfall and made use of stored soil moisture. Average weekly rainfall or soil moisture in the top 15 cm of soil, recorded from planting to 50% flowering, can be used to predict cowpea grain yield.

scholarly journals ANALYSIS OF THE TONLE SAP FLOOD PULSE BASED ON REMOTE SENSING: HOW MUCH DOES TONLE SAP LAKE AFFECT THE MEKONG RIVER FLOOD?

2018 ◽  
Vol XLII-3 ◽  
pp. 1461-1465
Author(s):  
W. Qu ◽  
N. Hu ◽  
J. Fu ◽  
J. Lu ◽  
H. Lu ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Time Lag ◽  
Economic Value ◽  
Water Storage ◽  
Remote Sensing Data ◽  
Flood Pulse ◽  
Mekong River ◽  
Lake Surface ◽  
Tonle Sap Lake ◽  
Tonle Sap

The economic value of the Tonle Sap Lake Floodplain to Cambodia is among the highest provided to a nation by a single ecosystem around the world. The flow of Mekong River is the primary factor affecting the Tonle Sap Lake Floodplain. The Tonle Sap Lake also plays a very important role in regulating the downstream flood of Mekong River. Hence, it is necessary to understand its temporal changes of lake surface and water storage and to analyse its relation with the flood processes of Mekong River. Monthly lake surface and water storage from July 2013 to May 2014 were first monitored based on remote sensing data. The relationship between water surface and accumulative water storage change was then established. In combination with hydrological modelling results of Mekong River Basin, the relation between the lake’s water storage and the runoff of Mekong River was analysed. It is found that the water storage has a sharp increase from September to December and, after reaching its maximum in December, water storage quickly decreases with a 38.8&amp;thinsp;billion&amp;thinsp;m<sup>3</sup> of drop in only half month time from December to January, while it keeps rather stable at a lower level in other months. There is a two months’ time lag between the maximum lake water storage and the Mekong River peak flood, which shows the lake’s huge flood regulation role to downstream Mekong River. It shows that this remote sensing approach is feasible and reliable in quantitative monitoring of data scarce lakes.

scholarly journals Fall Planting and Tree Shelters for Reforestation in the East Washington Cascades

2009 ◽  
Vol 24 (4) ◽  
pp. 173-179 ◽  
Author(s):  
Michael Taylor ◽  
Diane L. Haase ◽  
Robin L. Rose
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
High Elevation ◽  
Douglas Fir ◽  
Planting Date ◽  
Larix Occidentalis ◽  
Western Larch ◽  
Planting Dates ◽  
Tree Shelters

Abstract Reforestation on harsh, high-elevation sites near the crest of the Cascade Mountains in Washington can be challenging because of persistent snowpack and extreme climatic variation. The use of tree shelters was investigated with two species, Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) and western larch (Larix occidentalis Nutt.), on two Yakama Nation sites across three fall planting dates. For both species, seedlings inside tree shelters had increased survival compared with nonsheltered seedlings after one growing season despite increased damage by crushing from snowpack. Volumetric soil moisture content on the western larch site increased from 10% to 17% between the first and second planting dates, resulting in no effect of planting date on western larch survival. On the Douglas-fir site, however, soil moisture content was below 12% for all fall planting dates, resulting in only 2% survival for those seedlings planted on the first planting date. First-season seedling growth was unaffected by planting date or tree shelter treatment for both species. These results indicate the critical importance of soil moisture at time of planting and onset of precipitation after planting. Use of tree shelters may improve seedling survival on a harsh, high-elevation site, but it increases potential seedling damage because of crushing by snowpack.

Effect of planting date and density on calendula and peppermint herbs

2014 ◽  
Vol 1 (1) ◽  
pp. 25-29
Author(s):  
Rahim Mohammadian ◽  
Behnam Tahmasebpour ◽  
Peyvand Samimifar
Keyword(s):  
Mutual Effect ◽  
Dry Weight ◽  
Planting Date ◽  
Mass Reduction ◽  
Flower Number ◽  
Planting Dates ◽  
Randomized Design ◽  
Significant Difference ◽  
Completely Randomized Design ◽  
Total Maximum

A factorial experiment was conducted with a completely randomized design to evaluate the effects of planting date and density on calendula herbs and peppermint. It had 3 replicates and was done in Khosroshahr research farm, Tabriz in 2006. Under studied factors were: 3 planting dates (10 May, 25 May and 10 June) in 4 densities (25, 35, 45, 55) of the plant in square meters. The results of variance a nalysis showed that there was 1% probability significant difference between the effects of planting date and bush density on the leave number, bush height and the bush dry weight. But the mutual effect of the plant date in mentioned traits density was insignificant. Regarding the traits mean comparison, the total maximum dry weight was about the 55 bush density in mm. Also, the bush high density in mm causes the bush growth and its mass reduction. When there is the density grain, the flower number will increase due to bush grain in surface unit. Overall, we can conclude that 10 June planting and 45 bush density in mm is the most suitable items and results in favored production with high essence for these crops.

Nitrogen Demand of Cut Chrysanthemums in Relation to Shoot Height and Planting Date

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 523c-523
Author(s):  
Siegfried Zerche
Keyword(s):  
Dry Matter ◽  
Plant Density ◽  
Plant Biomass ◽  
N Uptake ◽  
Planting Date ◽  
Dry Matter Accumulation ◽  
Planting Dates ◽  
Shoot Height ◽  
Climate Conditions ◽  
Growing Period

Refined nutrient delivery systems are important for environmentally friendly production of cut flowers in both soil and hydroponic culture. They have to be closely orientated at the actual nutrient demand. To solve current problems, express analysis and nutrient uptake models have been developed in horticulture. However, the necessity of relatively laborious analysis or estimation of model input parameters have prevented their commercial use up to now. For this reason, we studied relationships between easily determinable parameters of plant biomass structure as shoot height, plant density and dry matter production as well as amount of nitrogen removal of hydroponically grown year-round cut chrysanthemums. In four experiments (planting dates 5.11.91; 25.3.92; 4.1.93; 1.7.93) with cultivar `Puma white' and a fixed plant density of 64 m2, shoots were harvested every 14 days from planting until flowering, with dry matter, internal N concentration and shoot height being measured. For each planting date, N uptake (y) was closely (r2 = 0.94; 0.93; 0.84; 0.93, respectively) related to shoot height (x) at the time of cutting and could be characterized by the equation y = a * × b. In the soilless cultivation system, dry matter concentrations of N remained constant over the whole growing period, indicating non-limiting nitrogen supply. In agreement with constant internal N concentrations, N uptake was linearly related (r2 = 0.94 to 0.99) to dry matter accumulation. It is concluded that shoot height is a useful parameter to include in a simple model of N uptake. However, in consideration of fluctuating greenhouse climate conditions needs more sophisticated approaches including processes such as water uptake and photosynthetically active radiation.

Multidecadal variability of the Tonle Sap Lake flood pulse regime

2021 ◽  
Author(s):  
Aifang Chen ◽  
Junguo Liu ◽  
Matti Kummu ◽  
Olli Varis ◽  
Qiuhong Tang ◽  
...  
Keyword(s):  
Flood Pulse ◽  
Pulse Regime ◽  
Multidecadal Variability ◽  
Tonle Sap Lake ◽  
Tonle Sap
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