Abstract
Abstract Agriculture contributes about 30 % of GDP growth in Cambodia and rice production is the most important agricultural activity. Eighty five percent of rice cultivation is conducted under rainfed lowland conditions, where the soils are typically infertile, sandy and acidic. Traditionally, after the rice crop is harvested the paddy fields are left fallow, due to a lack of irrigation and a lack of awareness of potential post-rice alternative cropping options. With the recent development and adoption of improved, photoperiod non-sensitive rice varieties, the opportunities for post-rice second cropping have increased. Among the second crop options are mungbean and peanut However, there remain significant production constraints to second cropping with legumes in the rainfed lowland rice environment, including infertile acidic soils, poor soil structure, and limited availability of water. To establish the ‘best-bet’ management options for mungbean and peanut cropping after rice in the rainfed lowland environment of Cambodia, this thesis examined a range of planting techniques, irrigation methods and irrigation frequency, and soil amendments (chemical fertiliser, lime, cow manure and mulch). The thesis reports the results from three field experiments and one glasshouse experiment which were conducted during the dry-season (November-March) in 2008-09 and 2009-10. The experiments were conducted at the Cambodian Agricultural Research and Development Institute (CARDI). It was hypothesised that : (i) the growth and grain yield of legumes would be improved by the use of single row raised beds; (ii) higher water use efficiency would potentially come from the use of double-row raised beds under conditions of infrequent water application; (iii) more frequent irrigation (every day, every 4 days) would result in higher total dry matter and higher grain yield, than with infrequent irrigation (every 8, 12 or 16 days); ( iv) the incorporation of cow manure into the crop seedbed would improve total dry matter and grain yield; (v) the use of chemical fertilizer, mulches and lime will all potentially improve the growth and yield of grain legumes. The results of field studies in the 2008-09 dry-season indicated that there were significant effects of planting bed formation on root depth and plant height at flowering, and on pod number per plant and grains per pod at maturity; however, these effects did not result in significant differences in final grain yield (GY), which for mungbean averaged 254 kg/ha and for peanut, 431 kg/ha. The frequency of irrigation had a significant effect on the final grain yield of peanut but not for mungbean. The GY and total dry matter (TDM) of peanut was reduced by 37 and 25 %, respectively, when the irrigation frequency was reduced from every 4, 8 or 12 days, to every 16 days. The results of the first field experiment in the 2009-10 dry-season indicated that for mungbean the use of drip irrigation three times per week gave the lowest GY (212 kg/ha), while hand-watering every three days produced the highest GY (575 kg/ha). There was no difference between GY for the furrow irrigation treatments every week (449 kg/ha) or every two weeks (453 kg/ha). For peanut, both drip irrigation and furrow irrigation at an interval of once every two weeks resulted in significant reductions in final grain yield of 25-47 % and 26 %, respectively, when compared with frequent irrigation regimes. Although peanut biomass was not reduced with the use of drip irrigation, final GY was low on account of the peanut pegs not being able to penetrate the soil. When compost mix was applied to the seedbed, there was no beneficial impact on crop establishment or final GY of either mungbean or peanut, while it reduced TDM for both legumes in the furrow and drip irrigation treatments. For the drip irrigation treatment with compost mix application, average TDM and GY for mungbean were reduced by 48 % and 57 %, respectively, relative to the other irrigation treatments, while under the least frequent irrigation regime (once every 14 days) there was an average reduction of TDM by 18.6 %. A glasshouse experiment conducted in the 2009-10 dry-season found that total dry matter and pod yield of mungbean and total dry matter of peanut of the treatments of omission of rice straw and chemical fertilizer was half of those in the all applied control, while the omission of compost mix and lime did not have any apparent effects on the growth and yield of either legume. A third experiment undertaken in the 2009-10 dry-season gave significantly higher mungbean grain yields (46 and 34 % higher) from furrow irrigation once per week and daily hand-watering, when compared with furrow irrigation once every two weeks. In addition, the water use efficiency in terms of TDM and GY for the furrow irrigation once per week and daily hand-watering, were significantly higher than furrow irrigation once every two weeks and hand watering three times per week. In summary, it was concluded that there was no difference in use of single row or double row raised beds in terms of the final grain yield of mungbean or peanut. However, the minimum irrigation frequency for optimising the yield of mungbean or peanut grown during the dry-season in the lowland environment needs to be at least once every week during the growing season. The incorporation of chemical fertilizer was the most important soil amendment for optimising growth and final grain yield for both legumes. The incorporation of lime only had a small effect due to the high initial soil pH. The potential value of the incorporation of compost mix remained inconclusive and probably requires further assessment to clarify the reasons for the apparent negative effect on crop growth recorded in this study. The incorporation of grain legumes into the rice-based cropping systems in the lowland rice environment of Cambodia, have the potential to significantly increase the income of smallholder farmer producers. While the GY of the legumes in these field experiments was relatively low (between 200 and 600 kg/ha), the gross value were often significantly better than that from rice. With an average peanut yield of 500 kg/ha the gross value was US$ 893/ha, while for mungbean the return ranged from between US$ 300 and US$ 900/ha, compared with US$ 595/ha for a rice crop with an average yield of 2500 kg/ha. For mungbean, the use of raised beds prevents water-logging, while weekly furrow irrigation was found to be adequate to ensure reasonable final yields. Over the cropping season mungbean required a total water application of approximately 270 mm, while for peanuts the requirement was about 345 mm. Further research is needed on aspects of varietal performance and pest management for both mungbean and peanut in the lowland rice based cropping systems of Cambodia.
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Claims 20
Claim · model-written summary
Planting bed formation significantly affected root depth, height, pod number and grains per pod.
- Taxon
- mungbean
.jpg?width=60)
Vigna radiatae1 - Treatment
- planting bed formatione0
- Outcome
- root depth and plant height at floweringe0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“there were significant effects of planting bed formation on root depth and plant height at flowering, and on pod number per plant and grains per pod at maturity”
t0“legume growth in rice-based cropping system”
e1“these effects did not result in significant differences in final grain yield (GY), which for mungbean averaged 254 kg/ha”
Claim · model-written summary
Planting bed formation did not significantly change final mungbean grain yield, averaging 254 kg/ha.
- Taxon
- mungbeanVigna radiatae0
- Treatment
- planting bed formatione1
- Outcome
- final grain yield (GY)e0
- Direction
- did not result in significant differencese0
- Value
- 254 kg/hae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these effects did not result in significant differences in final grain yield (GY), which for mungbean averaged 254 kg/ha”
e1“there were significant effects of planting bed formation on root depth and plant height at flowering, and on pod number per plant and grains per pod at maturity”
Claim · model-written summary
Planting bed formation did not significantly change final peanut grain yield, averaging 431 kg/ha.
- Taxon
- peanut
Arachis hypogaeae0 - Treatment
- planting bed formatione1
- Outcome
- final grain yield (GY)e0
- Direction
- did not result in significant differencese0
- Value
- 431 kg/hae0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“these effects did not result in significant differences in final grain yield (GY), which for mungbean averaged 254 kg/ha and for peanut, 431 kg/ha.”
e1“there were significant effects of planting bed formation on root depth and plant height at flowering, and on pod number per plant and grains per pod at maturity”
Claim · model-written summary
Irrigation frequency significantly affected peanut grain yield.
- Taxon
- peanutArachis hypogaeae0
- Treatment
- frequency of irrigatione0
- Outcome
- final grain yielde0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The frequency of irrigation had a significant effect on the final grain yield of peanut”
Claim · model-written summary
Irrigation frequency did not significantly affect mungbean grain yield.
- Taxon
- mungbeanVigna radiatae0
- Treatment
- frequency of irrigatione1
- Outcome
- final grain yielde1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“but not for mungbean.”
e1“The frequency of irrigation had a significant effect on the final grain yield of peanut”
Claim · model-written summary
Peanut grain yield fell 37% when irrigation interval reached 16 days.
- Taxon
- peanutArachis hypogaeae0
- Treatment
- every 16 dayse0
- Outcome
- GYe0
- Direction
- reducede0
- Value
- 37 and 25 %e0
- Comparator
- every 4, 8 or 12 dayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The GY and total dry matter (TDM) of peanut was reduced by 37 and 25 %, respectively, when the irrigation frequency was reduced from every 4, 8 or 12 days, to every 16 days.”
Claim · model-written summary
Peanut total dry matter fell 25% when irrigation interval reached 16 days.
- Taxon
- peanutArachis hypogaeae0
- Treatment
- every 16 dayse0
- Outcome
- total dry matter (TDM)e0
- Direction
- reducede0
- Value
- 25 %e0
- Comparator
- every 4, 8 or 12 dayse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The GY and total dry matter (TDM) of peanut was reduced by 37 and 25 %, respectively, when the irrigation frequency was reduced from every 4, 8 or 12 days, to every 16 days.”
Claim · model-written summary
For mungbean, drip irrigation three times weekly gave the lowest grain yield of 212 kg/ha.
- Taxon
- mungbeanVigna radiatae0
- Treatment
- drip irrigation three times per weeke0
- Outcome
- GYe0
- Direction
- loweste0
- Value
- 212 kg/hae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for mungbean the use of drip irrigation three times per week gave the lowest GY (212 kg/ha)”
Claim · model-written summary
For mungbean, hand watering every three days gave the highest grain yield of 575 kg/ha.
- Taxon
- mungbeanVigna radiatae1
- Treatment
- hand-watering every three dayse0
- Outcome
- GYe0
- Direction
- higheste0
- Value
- 575 kg/hae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“hand-watering every three days produced the highest GY (575 kg/ha)”
t0“legume growth in rice-based cropping system”
e1“these effects did not result in significant differences in final grain yield (GY), which for mungbean averaged 254 kg/ha”
Claim · model-written summary
Mungbean furrow irrigation weekly and fortnightly produced similar grain yields of 449 and 453 kg/ha.
- Taxon
- mungbeanVigna radiatae1
- Treatment
- furrow irrigation treatments every weeke0
- Outcome
- GYe0
- Direction
- no differencee0
- Value
- 449 kg/hae0
- Qualifier
- 453 kg/hae0
- Comparator
- every two weekse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was no difference between GY for the furrow irrigation treatments every week (449 kg/ha) or every two weeks (453 kg/ha).”
t0“legume growth in rice-based cropping system”
e1“these effects did not result in significant differences in final grain yield (GY), which for mungbean averaged 254 kg/ha”
Claim · model-written summary
Peanut drip irrigation reduced final grain yield by 25 to 47% against frequent irrigation.
- Taxon
- peanutArachis hypogaeae0
- Treatment
- drip irrigatione0
- Outcome
- final grain yielde0
- Direction
- reductionse0
- Value
- 25-47 %e0
- Comparator
- frequent irrigation regimese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For peanut, both drip irrigation and furrow irrigation at an interval of once every two weeks resulted in significant reductions in final grain yield of 25-47 % and 26 %, respectively, when compared with frequent irrigation regimes.”
Claim · model-written summary
Peanut furrow irrigation every two weeks reduced final grain yield by 26% against frequent irrigation.
- Taxon
- peanutArachis hypogaeae0
- Treatment
- furrow irrigation at an interval of once every two weekse0
- Outcome
- final grain yielde0
- Direction
- reductionse0
- Value
- 26 %e0
- Comparator
- frequent irrigation regimese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For peanut, both drip irrigation and furrow irrigation at an interval of once every two weeks resulted in significant reductions in final grain yield of 25-47 % and 26 %, respectively, when compared with frequent irrigation regimes.”
Claim · model-written summary
Peanut biomass was not reduced under drip irrigation.
- Taxon
- peanutArachis hypogaeae0
- Treatment
- drip irrigatione0
- Outcome
- peanut biomasse0
- Direction
- not reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Although peanut biomass was not reduced with the use of drip irrigation”
Claim · model-written summary
Peanut peg failure to penetrate soil explained low final grain yield under drip irrigation.
- Taxon
- peanutArachis hypogaeae0
- Organ / stage
- peanut pegse0
- Outcome
- final GYe0
- Qualifier
- not being able to penetrate the soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“final GY was low on account of the peanut pegs not being able to penetrate the soil.”
Claim · model-written summary
Compost mix did not benefit crop establishment or final grain yield of mungbean.
- Taxon
- mungbeanVigna radiatae0
- Treatment
- compost mixe0
- Outcome
- crop establishment or final GYe0
- Direction
- no beneficial impacte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When compost mix was applied to the seedbed, there was no beneficial impact on crop establishment or final GY of either mungbean or peanut”
Claim · model-written summary
Compost mix did not benefit crop establishment or final grain yield of peanut.
- Taxon
- peanutArachis hypogaeae0
- Treatment
- compost mixe0
- Outcome
- crop establishment or final GYe0
- Direction
- no beneficial impacte0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When compost mix was applied to the seedbed, there was no beneficial impact on crop establishment or final GY of either mungbean or peanut”
Claim · model-written summary
Omission of rice straw and chemical fertilizer halved mungbean total dry matter and pod yield against the complete treatment.
- Taxon
- mungbeanVigna radiatae0
- Treatment
- omission of rice straw and chemical fertilizere0
- Outcome
- total dry matter and pod yielde0
- Direction
- halfe0
- Value
- halfe0
- Comparator
- all applied controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total dry matter and pod yield of mungbean and total dry matter of peanut of the treatments of omission of rice straw and chemical fertilizer was half of those in the all applied control”
Claim · model-written summary
Omission of rice straw and chemical fertilizer halved peanut total dry matter against the complete treatment.
- Taxon
- peanutArachis hypogaeae0
- Treatment
- omission of rice straw and chemical fertilizere0
- Outcome
- total dry mattere0
- Direction
- halfe0
- Value
- halfe0
- Comparator
- all applied controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total dry matter and pod yield of mungbean and total dry matter of peanut of the treatments of omission of rice straw and chemical fertilizer was half of those in the all applied control”
Claim · model-written summary
Weekly furrow irrigation increased mungbean yield 46% relative to fortnightly furrow irrigation.
- Taxon
- mungbeanVigna radiatae0
- Treatment
- furrow irrigation once per weeke0
- Outcome
- grain yieldse0
- Direction
- highere0
- Value
- 46 and 34 %e0
- Comparator
- furrow irrigation once every two weekse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significantly higher mungbean grain yields (46 and 34 % higher) from furrow irrigation once per week and daily hand-watering, when compared with furrow irrigation once every two weeks.”
Claim · model-written summary
Daily hand watering increased mungbean yield 34% relative to fortnightly furrow irrigation.
- Taxon
- mungbeanVigna radiatae0
- Treatment
- daily hand-wateringe0
- Outcome
- grain yieldse0
- Direction
- highere0
- Value
- 34 %e0
- Comparator
- furrow irrigation once every two weekse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significantly higher mungbean grain yields (46 and 34 % higher) from furrow irrigation once per week and daily hand-watering, when compared with furrow irrigation once every two weeks.”
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