The effects of N fertilizer and soil moisture on the nodulation and growth of Phaseolus vulgaris

1984 ◽  
Vol 103 (1) ◽  
pp. 87-93 ◽  
Author(s):  
Siu M. T. Saito ◽  
Maria Nazareth S. Montanheiro ◽  
R. L. Victoria ◽  
K. Reichardt

SummarySoil water content affected the nodulation and N2 fixation of Phaseolus vulgaris by Rhizobium phaseoli and the utilization of mineral N by plants. Plants grown in wet soil produced twice as much as those grown on dry soils. Nodule weight and activity were five to ten times greater than those from dry soils. At 45 days, N additions inhibited nodulation, but this effect was partially diminished in wet soils.The maximum N utilization from fertilizer to produce dry matter did not correspond to maximum N utilization by pods.

2013 ◽  
Vol 27 (3) ◽  
pp. 351-357 ◽  
Author(s):  
A. Pérez-Vázquez ◽  
G. Hernández-Salinas ◽  
C. Ávila-Reséndiz ◽  
O.A. Valdés-Rodríguez ◽  
F. Gallardo-López ◽  
...  

Abstract The purpose of this study was to evaluate growth, chlorophyll content, and photosynthesis in Jatropha at different levels of soil moisture. Plants were cultivated in containers and the treatments of the soil water content evaluated were: 0% (without watering), 20, 40, 60, and 80% soil water content. Plant height was statistically similar for all treatments, but the number of leaves differed significantly. Total dry matter and chlorophyll at 40, 60, and 80% soil water content were statistically similar, but different from 0 and 20% soil water content. Leaf area at 40, 60, and 80% soil water content was statistically different from 0 and 20% soil water content. The photosynthetic rate, transpiration and stomatal conductance at 60 and 80% soil water content were statistically similar but different from 0 and 20% soil water content. Water stress affected growth, chlorophyll content, photosynthetic rate, transpiration, and stomatal conductance.


2022 ◽  
Vol 277 ◽  
pp. 108420
Author(s):  
Stephen Okoth Aluoch ◽  
Zhuoting Li ◽  
Xiaoxin Li ◽  
Chunsheng Hu ◽  
David M. Mburu ◽  
...  

2009 ◽  
Vol 6 (5) ◽  
pp. 6425-6454
Author(s):  
H. Stephen ◽  
S. Ahmad ◽  
T. C. Piechota ◽  
C. Tang

Abstract. The Tropical Rainfall Measuring Mission (TRMM) carries aboard the Precipitation Radar (TRMMPR) that measures the backscatter (σ°) of the surface. σ° is sensitive to surface soil moisture and vegetation conditions. Due to sparse vegetation in arid and semi-arid regions, TRMMPR σ° primarily depends on the soil water content. In this study we relate TRMMPR σ° measurements to soil water content (ms) in Lower Colorado River Basin (LCRB). σ° dependence on ms is studied for different vegetation greenness values determined through Normalized Difference Vegetation Index (NDVI). A new model of σ° that couples incidence angle, ms, and NDVI is used to derive parameters and retrieve soil water content. The calibration and validation of this model are performed using simulated and measured ms data. Simulated ms is estimated using Variable Infiltration Capacity (VIC) model whereas measured ms is acquired from ground measuring stations in Walnut Gulch Experimental Watershed (WGEW). σ° model is calibrated using VIC and WGEW ms data during 1998 and the calibrated model is used to derive ms during later years. The temporal trends of derived ms are consistent with VIC and WGEW ms data with correlation coefficient (R) of 0.89 and 0.74, respectively. Derived ms is also consistent with the measured precipitation data with R=0.76. The gridded VIC data is used to calibrate the model at each grid point in LCRB and spatial maps of the model parameters are prepared. The model parameters are spatially coherent with the general regional topography in LCRB. TRMMPR σ° derived soil moisture maps during May (dry) and August (wet) 1999 are spatially similar to VIC estimates with correlation 0.67 and 0.76, respectively. This research provides new insights into Ku-band σ° dependence on soil water content in the arid regions.


Biologia ◽  
2007 ◽  
Vol 62 (5) ◽  
Author(s):  
Horst Gerke ◽  
Rolf Kuchenbuch

AbstractPlants can affect soil moisture and the soil hydraulic properties both directly by root water uptake and indirectly by modifying the soil structure. Furthermore, water in plant roots is mostly neglected when studying soil hydraulic properties. In this contribution, we analyze effects of the moisture content inside roots as compared to bulk soil moisture contents and speculate on implications of non-capillary-bound root water for determination of soil moisture and calibration of soil hydraulic properties.In a field crop of maize (Zea mays) of 75 cm row spacing, we sampled the total soil volumes of 0.7 m × 0.4 m and 0.3 m deep plots at the time of tasseling. For each of the 84 soil cubes of 10 cm edge length, root mass and length as well as moisture content and soil bulk density were determined. Roots were separated in 3 size classes for which a mean root porosity of 0.82 was obtained from the relation between root dry mass density and root bulk density using pycnometers. The spatially distributed fractions of root water contents were compared with those of the water in capillary pores of the soil matrix.Water inside roots was mostly below 2–5% of total soil water content; however, locally near the plant rows it was up to 20%. The results suggest that soil moisture in roots should be separately considered. Upon drying, the relation between the soil and root water may change towards water remaining in roots. Relations depend especially on soil water retention properties, growth stages, and root distributions. Gravimetric soil water content measurement could be misleading and TDR probes providing an integrated signal are difficult to interpret. Root effects should be more intensively studied for improved field soil water balance calculations.


2002 ◽  
Vol 82 (4) ◽  
pp. 855-859 ◽  
Author(s):  
M. L. Leblanc ◽  
D. C. Cloutier ◽  
C. Hamel

A 2-year field study was conducted in corn to determine the influence of rainfall, irrigation and soil water content on common lambsquarters and barnyardgrass emergence. Rainfall or irrigation had no influence on the final weed density and little on the pattern of weed emergence because the soil water content was at or greater than field capacity during the main weed emergence period. Irrigation may hasten the first weed emergence by warming the soil when temperature is limiting for germination. In southwestern Quebec, temperature appears to be the most important factor regulating germination in the spring since soil moisture is normally at field capacity for a long period, in part because of the melting of snow. Key words: Irrigation, weed emergence, soil moisture


2009 ◽  
Vol 16 (1) ◽  
pp. 141-150 ◽  
Author(s):  
M. Gebremichael ◽  
R. Rigon ◽  
G. Bertoldi ◽  
T. M. Over

Abstract. By providing continuous high-resolution simulations of soil moisture fields, distributed hydrologic models could be powerful tools to advance the scientific community's understanding of the space-time variability and scaling characteristics of soil moisture fields. However, in order to use the soil moisture simulations from hydrologic models with confidence, it is important to understand whether the models are able to represent in a reliable way the processes regulating soil moisture variability. In this study, a comparison of the scaling characteristics of spatial soil moisture fields derived from a set of microwave radiometer observations from the Southern Great Plains 1997 experiment and corresponding simulations using the distributed hydrologic model GEOtop is performed through the use of generalized variograms. Microwave observations and model simulations are in agreement with respect to suggesting the existence of a scale-invariance property in the variograms of spatial soil moisture fields, and indicating that the scaling characteristics vary with changes in the spatial average soil water content. However, observations and simulations give contradictory results regarding the relationship between the scaling parameters (i.e. spatial organization) and average soil water content. The drying process increased the spatial correlation of the microwave observations at both short and long separation distances while increasing the rate of decay of correlation with distance. The effect of drying on the spatial correlation of the model simulations was more complex, depending on the storm and the simulation examined, but for the largest storm in the simulation most similar to the observations, drying increased the long-range correlation but decreased the short-range. This is an indication that model simulations, while reproducing correctly the total streamflow at the outlet of the watershed, may not accurately reproduce the runoff production mechanisms. Consideration of the scaling characteristics of spatial soil moisture fields can therefore serve as a more intensive means for validating distributed hydrologic models, compared to the traditional approach of only comparing the streamflow hydrographs.


1966 ◽  
Vol 6 (20) ◽  
pp. 48
Author(s):  
LJ Phillips ◽  
MJT Norman

A multifactorial experiment comprising combinations of three pre-wet-season chisel ploughing treatments, three wet-season chisel ploughing treatments, and three inter-row cultivation treatments was carried out on bulrush millet (Pennisetum typhoides S. & H.) at Katherine, N.T., in 1963-64, and was repeated in 1964-65. Pre-wet-season ploughing throughout the growth of the nitrogen yield of millet when treatments had very little effect on the dry matter or nitrogen yield of millet crop. Increasing the depth of wet-season ploughing increased the dry matter and sampled at 7 and 12 weeks after sowing, but at the final sampling, 18 weeks after sowing, only the differences in dry matter yield were maintained. Responses in dry matter and nitrogen yield were obtained to one inter-row cultivation, but not to a second. Differences in dry matter yield due to wetseason ploughing and inter-row cultivation were associated with differences in soil water content measured in the 1-4 feet profile in 1964-65.


2014 ◽  
Vol 6 (4) ◽  
pp. 125 ◽  
Author(s):  
Anne Karuma ◽  
Peter Mtakwa ◽  
Nyambilila Amuri ◽  
Charles K. Gachene ◽  
Patrick Gicheru

Soil water conservation through tillage is one of the appropriate ways of addressing soil moisture deficit in rainfed agriculture. This study evaluated the effects of tillage practices on soil moisture conservation and crop yields in Mwala District, Eastern Kenya during the long rains (LR) and short rains (SR) of 2012/13. Six tillage systems: Disc plough (MB), Disc plough and harrowing (MBH), Ox-ploughing (OX), Subsoiling – ripping (SR), Hand hoe and Tied Ridges (HTR) and Hand hoe only (H) and, three cropping systems namely, sole maize, sole bean and maize - bean intercrop, were investigated in a split-plot design with four replicates. Data on soil water content was monitored at different weeks after planting and the crop yields at end of each growing season. A three-season average shows that soil water content and crop yields were higher in conventional tillage methods compared to the conservation tillage methods. Long term tillage experiments are thus required at different locations, under various environmental and soil conditions to validate the study findings.


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