The water balance of post-monsoonal dryland crops

SUMMARYSix dryland crops (mungbean, cow pea, soya bean, groundnut, maize and sorghum) and two rice cultivars (C·171·136 and IR 36) were grown under rainfed and irrigated conditions on a dryland site with a clay loam soil at the International Rice Research Institute, Philippines. After the first 30 days of growth there was no effective rain, and the rainfed crops encountered different water deficits. Crop productivity, leaf area, plant water status, root distribution, and soil water use were measured.Neither rice cultivar yielded seed under rainfed conditions, but all other crops did. With mungbean and cow pea there was little difference between the yields under rainfed and irrigated conditions, but groundnut, soya bean, sorghum and maize gave higher yields under irrigation.The rainfed crops extracted different amounts of stored soil water, ranging from 100 mm for IR 36 to 250 mm for groundnut. The different amounts were associated with different growth durations, rooting depths and rates of soil water depletion from within the root zone. Biological productivity of the six rainfed crops with the C 3 photosynthetic pathway was linearly related to transpiration, which was estimated from soil water extraction and soil evaporation. Biological productivity per unit of transpiration for the two crops with the C 4 pathway was 2·2 times higher than for those with the C 3 pathway. The different seed yields of the rainfed crops were due to differences in harvest index and the chemical composition of seeds, as well as to biological productivity.The results are discussed in relation to the potential for growing dryland crops after rice in rice-based cropping systems.

Download Full-text

Vertical Distribution of Pratylenchus spp. in Silt Loam Soil and Pacific Northwest Dryland Crops

Plant Disease ◽

10.1094/pdis-92-12-1662 ◽

2008 ◽

Vol 92 (12) ◽

pp. 1662-1668 ◽

Cited By ~ 17

Author(s):

Richard W. Smiley ◽

Jason G. Sheedy ◽

Sandra A. Easley

Keyword(s):

Vertical Distribution ◽

Pacific Northwest ◽

Cropping Systems ◽

Lesion Nematodes ◽

The Pacific ◽

Loam Soil ◽

Dryland Crops ◽

Root Lesion Nematodes ◽

The Vertical Distribution ◽

Summer Fallow

Dryland field crops in the Pacific Northwest United States are commonly produced in silt loams infested by the root-lesion nematodes Pratylenchus neglectus and P. thornei. Soils at 30 sites in Oregon were sampled from 0 to 120 cm depth to examine the vertical distribution of these Pratylenchus spp. Both species were distributed through entire soil profiles of all cropping systems. Populations were generally greatest in the surface 30 cm, but sometimes high populations were detected at depths greater than 45 cm. Sampling to 30 cm depth allowed detection of more than 50% of the population in most sites, while sampling to 45 cm depth yielded more than 75% of the population in over 75% of the sites evaluated. Therefore, soil samples should be collected to 30 to 45 cm depth to accurately estimate populations of Pratylenchus spp. in dryland crops produced on silt loams in the Pacific Northwest. Populations of Pratylenchus spp. were found to be related to the most recently planted crop, with populations after barley, after wheat, and during summer fallow being detected in ascending order.

Download Full-text

Participatory research in dryland cropping systems — monitoring and simulation of soil water and nitrogen in farmers' paddocks in Central Queensland

Australian Journal of Experimental Agriculture ◽

10.1071/ea02205 ◽

2004 ◽

Vol 44 (3) ◽

pp. 321 ◽

Cited By ~ 10

Author(s):

M. A. Foale ◽

M. E. Probert ◽

P. S. Carberry ◽

D. Lack ◽

S. Yeates ◽

...

Keyword(s):

Soil Water ◽

Service Providers ◽

Production Systems ◽

Cropping Systems ◽

Management Strategies ◽

Cropping System ◽

Crop Productivity ◽

Mineral Nitrogen ◽

Soil Behaviour ◽

On Farm

Collaboration of researchers and service-providers with farmers in addressing crop and soil management, using on-farm experiments and cropping system simulation, was negotiated in 2 districts in Central Queensland, Australia. The 2 most influential variables affecting crop productivity in this region (soil water and mineral nitrogen contents) and the growth of sown crops, were monitored and simulated for 3 years beginning in December 1992. Periodic soil sampling of large experimental strips on 3 farms, from paddocks that differed in cropping history and soil properties, provided robust datasets of change, over time, of soil water and mineral nitrogen status. Farmers participated in twice-yearly discussions with researchers, informed by the accumulating data, which influenced thinking about soil behaviour and possible new management strategies. As the study period coincided with a prolonged drought, so that cropping opportunities were few, the objectives of the work were modified to concentrate almost exclusively on the soil variables.The contribution of the Agricultural Production Systems Simulator, which was used to simulate the measured changes in soil water and mineral nitrogen, was found by all participants to be useful. The APSIM output generally demonstrated close correspondence with field observations, which raised confidence in its applicability to local cropping systems. Exploration of hypothetical situations of interest to farmer participants, in the form of what-if scenarios, provided insights into the behaviour of the production system for a range of soil and seasonal conditions. The informed speculation of the simulator became a substitute for the farmers' own, more tentative, efforts.The regular participative review sessions proved to be highly effective in stimulating the learning of both farmers and researchers. The farmers were able to feel comfortable as owners of the collaborative experiments and custodians of the learning environment. Clear evidence for the ongoing learning of these farmers appeared in post-collaboration practices and experiences.

Download Full-text

Physiological Responses of Carambola Trees to Soil Water Depletion

HortScience ◽

10.21273/hortsci.40.7.2145 ◽

2005 ◽

Vol 40 (7) ◽

pp. 2145-2150 ◽

Cited By ~ 1

Author(s):

Rashid Al-Yahyai ◽

Bruce Schaffer ◽

Frederick S. Davies

Keyword(s):

Soil Water ◽

Leaf Gas Exchange ◽

Water Status ◽

Field Capacity ◽

Soil Water Depletion ◽

Gas Exchange Parameters ◽

Water Depletion ◽

Physiological Variables ◽

Loam Soil ◽

Exchange Parameters

Two-year-old `Arkin' carambola (Averrhoa carambola L.) trees were grown in containers in a greenhouse and the field in a very gravelly loam soil. Trees in the field were subjected to four soil water depletion (SWD) levels which averaged, 10.5%, 26.5%, 41.0%, and 55.5% and trees in the greenhouse were maintained at field capacity or dried continuously to produce a range of SWD levels. The relationships between SWD and leaf (ΨL) and stem (Ψs) water potential, net CO2 assimilation (ACO2), stomatal conductance of water (gs) and transpiration (E) were determined. Coefficients of determination values between physiological variables were higher for trees in the greenhouse than in the field, which may have been due to greater fluctuations in vapor pressure deficit (VPD) in the field. Soil water depletion levels above 50% caused a reduction in Ψs that subsequently decreased gs. This reduction in Ψs was correlated with a linear reduction in E and a considerable decline in ACO2 when gs fell below about 50 mmol·m–2 ·s–1. Leaf gas exchange parameters were better correlated with Ψs than with SWD level. Therefore, Ψs may be a better predictor of carambola tree water status than SWD in a well-drained, very gravelly loam soil.

Download Full-text

Using short-term ensemble weather forecast to evaluate outcomes of irrigation

10.5194/egusphere-egu21-4210 ◽

2021 ◽

Author(s):

Danlu Guo ◽

Andrew Western ◽

Quan Wang ◽

Dongryeol Ryu ◽

Peter Moller ◽

...

Keyword(s):

Soil Water ◽

Root Zone ◽

Water Status ◽

Water Productivity ◽

Limited Resource ◽

Weather Forecast ◽

Irrigation Scheduling ◽

Irrigation Event ◽

Optimal Timing ◽

Short Term

Irrigation water is an expensive and limited resource. Previous studies show that irrigation scheduling can boost efficiency by 20-60%, while improving water productivity by at least 10%. In practice, scheduling decisions are often needed several days prior to an irrigation event, so a key aspect of irrigation scheduling is the accurate prediction of crop water use and soil water status ahead of time. This prediction relies on several key inputs such as soil water, weather and crop conditions. Since each input can be subject to its own uncertainty, it is important to understand how these uncertainties impact soil water prediction and subsequent irrigation scheduling decisions.This study aims to evaluate the outcomes of alternative irrigation scheduling decisions under uncertainty, with a focus on the uncertainties arising from short-term weather forecast. To achieve this, we performed a model-based study to simulate crop root-zone soil water content, in which we comprehensively explored different combinations of ensemble short-term rainfall forecast and alternative decisions of irrigation scheduling. This modelling produced an ensemble of soil water contents to enable quantification of risks of over- and under-irrigation; these ensemble estimates were summarized to inform optimal timing of next irrigation event to minimize both the risks of stressing crop and wasting water. With inclusion of other sources of uncertainty (e.g. soil water observation, crop factor), this approach shows good potential to be extended to a comprehensive framework to support practical irrigation decision-making for farmers.

Download Full-text

Sensitivity of Continuous and Discrete Plant and Soil Water Status Monitoring in Peach Trees Subjected to Deficit Irrigation

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.124.4.437 ◽

1999 ◽

Vol 124 (4) ◽

pp. 437-444 ◽

Cited By ~ 107

Author(s):

David A. Goldhamer ◽

Elias Fereres ◽

Merce Mata ◽

Joan Girona ◽

Moshe Cohen

Keyword(s):

Water Potential ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Deficit Irrigation ◽

Root Zone ◽

Water Status ◽

Full Irrigation ◽

Trunk Diameter ◽

Peach Trees

To characterize tree responses to water deficits in shallow and deep rooted conditions, parameters developed using daily oscillations from continuously measured soil water content and trunk diameter were compared with traditional discrete monitoring of soil and plant water status in lysimeter and field-grown peach trees [Prunus persica (L.) Batsch `O'Henry']. Evaluation occurred during the imposition of deficit irrigation for 21 days followed by full irrigation for 17 days. The maximum daily available soil water content fluctuations (MXAWCF) taken at any of the four monitored root zone depths responded most rapidly to the deficit irrigation. The depth of the MXAWCF increased with time during the deficit irrigation. Differences relative to a fully irrigated control were greater in the lysimeter than the field-grown trees. Minimum daily trunk diameter (MNTD) and maximum daily trunk shrinkage (MDS) responded sooner than midday stem water potential (stem Ψ), predawn or midday leaf water potential (predawn leaf Ψ and leaf Ψ), or photosynthesis (A). Parameters based on trunk diameter monitoring, including maximum daily trunk diameter (MXTD), correlated well with established physiological parameters of tree water status. Statistical analysis of the differences in the measured parameters relative to fully irrigated trees during the first 10 days of deficit irrigation ranked the sensitivity of the parameters in the lysimeter as MXAWCF > MNTD > MDS > MXTD > stem Ψ = A = predawn leaf Ψ = leaf Ψ. Equivalent analysis with the field-grown trees ranked the sensitivity of the parameters as MXAWCF > MNTD > MDS > stem Ψ = leaf Ψ = MXTD = predawn leaf Ψ > A. Following a return to full irrigation in the lysimeter, MDS and all the discrete measurements except A quickly returned to predeficit irrigation levels. Tree recovery in the field-grown trees was slower and incomplete due to inadequate filling of the root zone. Fruit size was significantly reduced in the lysimeter while being minimally affected in the field-grown trees. Parameters only available from continuous monitoring hold promise for improving the precision of irrigation decision-making over the use of discrete measurements.

Download Full-text

Soil water status and growth of tomato with partial root-zone drying and deficit drip irrigation techniques

Irrigation Science ◽

10.1007/s00271-019-00658-y ◽

2019 ◽

Vol 38 (2) ◽

pp. 163-176 ◽

Cited By ~ 4

Author(s):

Mohamed A. Mattar ◽

Tarek K. Zin El-Abedin ◽

A. A. Alazba ◽

Hussein M. Al-Ghobari

Keyword(s):

Soil Water ◽

Drip Irrigation ◽

Root Zone ◽

Water Status ◽

Soil Water Status

Download Full-text

Differential effects of soil water deficit on the basic plant functions and their significance to analyse crop responses to water deficit in indeterminate plants

Australian Journal of Agricultural Research ◽

10.1071/ar05066 ◽

2005 ◽

Vol 56 (11) ◽

pp. 1201 ◽

Cited By ~ 33

Author(s):

Jacques Wery

Keyword(s):

Exchange Rate ◽

Soil Water ◽

Water Deficit ◽

Root Zone ◽

Water Status ◽

Large Set ◽

Soil Water Deficit ◽

Carbon Exchange ◽

Differential Effects ◽

Basic Plant

On the basis of a large set of experiments conducted on legumes, cotton, and vineyards, we propose a framework to analyse the functioning of an indeterminate crop in response to soil water deficit. Indicators of basic plant functions (e.g. leaf carbon exchange rate as an indicator of production of assimilates) have been correlated with soil water status in the root zone (quantified with the fraction of transpirable soil water, FTSW), across a range of soil water deficit. Leaf area development was the most sensitive process to soil water deficits, with branching being more sensitive than leaf emission and growth on the main stem. Net carbon exchange rate and the various steps of reproductive development were less sensitive to drought, thereby explaining why grain/fruit yield can be increased by a moderate drought in indeterminate plants. Other traits of plant adaptation to drought at the crop level, such as reduction of flowering duration and increase of harvest index (in case of early drought), can be explained by the observed differential effects of soil dehydration on the various plant functions. These results have been used to develop regulated deficit irrigation strategies using tensiometers and tools for in-field diagnosis, especially for seed production and grape production.

Download Full-text

Sweet corn crop response to different dripline spacings in the dry Mediterranean area

Acta agriculturae Slovenica ◽

10.14720/aas.2020.116.1.1382 ◽

2020 ◽

Vol 116 (1) ◽

pp. 125

Author(s):

Ibrahim MUBARAK ◽

Mussaddak JANAT

Keyword(s):

Soil Water ◽

Irrigation Water ◽

Sweet Corn ◽

Unit Area ◽

Irrigation System ◽

Water Status ◽

Cost Savings ◽

Mediterranean Area ◽

Irrigation Water Use ◽

Loam Soil

Increasing the spacing between driplines is the most significant factor in reducing the high initial costs of drip irrigation system. A two-year field study (2017 and 2018) was conducted on a clay loam soil to evaluate the effects of different dripline spacings (75, 150, 225, and 300 cm) on sweet corn yields, soil water status, and irrigation water use efficiency (IWUE) in the dry Mediterranean area. Results showed that the average husked cob yield (HCY) and IWUE were significantly decreased as the dripline spacing increased. HCY was 13.93, 12.30, 9.18, and 6.86 t ha-1, for dripline spacing of 75, 150, 225, and 300 cm, respectively, for an average irrigation water depth of 725 mm. Both soil water storages and yields decreased with distance from the dripline. The 150-, 225- and 300 cm dripline spacings yielded 11.7, 34.0 and 50.8 % less than the 75 cm dripline spacing, but these wider dripline spacings provided 50, 67 and 75 % less unit-area cost, respectively. However, these reductions in crop yield did not justify the extra cost of the closer dripline spacing, at low crop prices and high dripline costs. Finally, further studies are needed to benefit from the higher initial unit-area cost savings obtained under the wider dripline spacings.

Download Full-text