Iron toxicity to rice in an acid sulfate soil as influenced by water regimes

Summary The effects of two water regimes: Continuous flooding and flooding with soil drying on iron toxicity to rice in an acid sulfate soil was studied by continuously growing 7 crops of IR-32 rice in pots under the two water treatments. There was no plant growth upto the second crop under both water treatments due to iron toxicity. But there was good growth of rice under the continuous water regime from third cropping onwards, however, there was no growth of rice in the flooding with soil drying treatment even upto the seventh crop due to iron toxicity.The results of the study bring out that keeping an acid sulfate soil flooded for a few weeks and then planting rice when iron in soil solution has dropped below toxicity level may be a possible management practice for lowland rice culture on such soils. Drying and reflooding an acid sulfate soil on the other hand aggravates soil acidity and keeps iron in solution in high amounts to be toxic to rice plant.     

The effects of soil drying and rewetting on rice growth in lowland aquatic Ferralsols in the southeastern forest region of Madagascar

In the southeastern-forest region of Madagascar, the year-around anaerobic condition of most lowlands favors soil organic matter (SOM) accumulation, while the inherently nutrient-poor soils limit rice yields. Accelerating decomposition of the accumulated SOM through the soil surface drainage before transplanting is a conceivable approach to improve rice production. However, the effect of soil drying on rice growth has been little studied in highly weathered Ferralsols. A pot experiment was conducted to examine the soil-drying effect on rice growth. One-month period of the soil drying before transplanting substantially increased the biomass production compared to those grown in the continuously submerged soils, which was mainly attributable to the large N uptakes derived from the ‘soil-drying effect’. However, soil-drying treatment decreased the physiological nitrogen use efficiency (PNUE: gBiomass/gNuptake) associated with the reduced plant P and K concentrations. Application of NPK fertilizer ameliorated the PNUE, and plant P and K concentrations. However, the plant K and Si dilution with soil-drying treatment and plant Si dilution with NPK fertilizer application negatively affected grain fertility due to blast infection. Our study indicated balanced nutrient management would be important to maximize the benefit of the soil-drying effect, and to prevent biotic damages to rice plants.     

Nitrogen losses in puddled soils as affected by timing of water deficit and nitrogen fertilization

Erratic rainfall in rainfed lowlands and inadequate water supply in irrigated lowlands can results in alternate soil drying and flooding during a rice (Oryza sativa L.) cropping period. Effects of alternate soil drying and flooding on N loss by nitrification-denitrification have been inconsistent in previous field research. To determine the effects of water deficit and urea timing on soil NO₃ and NH₄, floodwater NO₃, and N loss from added ¹⁵N-labeled urea, a field experiment was conducted for 2 yr on an Andaqueptic Haplaquoll in the Philippines. Water regimes were continuously flooded, not irrigated from 15 to 35 d after transplanting (DT), or not irrigated from 41 to 63 DT. The nitrogen treatments in factorial combination with water regimes were no applied N and 80 kg urea-N ha^–1, either applied half basally and half at 37 DT or half at 11 DT and half at 65 DT. Water deficit at 15 to 35 DT and 41 to 63 DT, compared with continuous soil flooding, significantly reduced extractable NH₄ in the top 30-cm soil layer and resulted in significant but small (<1.0 kg N ha^–1) soil NO₃ accumulations. Soil NO₃, which accumulated during the water deficit, rapidly disappeared after reflooding. Water deficit at 15 to 35 DT, unlike that at 41 to 63 DT, increased the gaseous loss of added urea N as determined from unrecovered ¹⁵N in ¹⁵N balances. The results indicate that application of urea to young rice in saturated or flooded soil results in large, rapid losses of N (mean = 35% of applied N), presumably by NH₃ volatilization. Subsequent soil drying and flooding during the vegetative growth phase can result in additional N loss (mean = 14% of applied N), presumably by nitrification-denitrification. This additional N loss due to soil drying and flooding decreases with increasing crop age, apparently because of increased competition by rice with soil microorganisms for NH₄ and NO₃.     

Availability and utilization of fertilizer nitrogen by rice under alternate flooding

Summary A greenhouse pot experiment with three N sources—¹⁵N-depleted ammonium sulfate, urea and sulfur-coated urea (SCU), three N levels—0, 50 and 200 ppm, and three irrigation treatments was conducted with rice in an Alamo clay soil. The irrigation treatments consisted of continuous flooding, alternating flooded-saturated and alternating flooded-drained conditions. The kinetics of NH ₄ ⁺ and NH ₄ ⁺ +NO ₃ ⁻ (available N) in soil was investigated under rice culture. Alternating flooded-drained conditions maintained a significantly lower level of available N in the soil than the other irrigation treatments. Among the N sources evaluated, urea and A/S had similar effects but SCU maintained significantly lower levels of available N in the soil during the growth of rice. Appreciable quantities of NO ₃ ⁻ accumulated during the draining periods of alternating flooded-drained treatments were apparently lost from the soil system upon reflooding.     

Soil and fertilizer nitrogen transformations under alternate flooding and drying moisture regimes

Summary A study of changes in NH₄ ⁺ and NO₃ ^––N in Maahas clay amended with (NH₄)₂SO₄ and subjected to 4 water regimes in the presence and absence of the nitrification inhibitor N-Serve (Nitrapyrin) showed that the mineral N was well conserved in the continoous regimes of 50% and 200% (soil weight basis) but suffered heavy losses due to nitrification-denitrification under alternate drying and flooding. N-Serve was effective in minimizing these losses.Another incubation study with 3 soils showed that after 10 cycles of flooding and drying (either at 60°C or 25°C), the ammonification of soil N was enhanced. Nitrification of soil as well as fertilizer NH₄ ⁺ was completely inhibited upto 4 weeks by the treatments involving drying at high temperature. Flooding and air drying at 25°C, on the other hand, enhanced ammonification of soil N but retarded nitrification. These treatments, however, enhanced both ammonification and nitrification of the applied NH₄ ⁺ fertilizer N. Under flooded conditions rate of NH₄ ⁺ production was faster in soils that were dried at 60°C or 25°C and then flooded as compared to air dried soils.It is concluded that N losses by nitrification-denitrification and related N transformations may be considerably altered by alternating moisture regimes. Flooding and drying treatments seem to retard nitrification of soil N but conserve that of fertilizer NH₄ ⁺ applied after these treatments.     

冬作季节土地管理对水稻土CH_4排放季节变化的影响

通过温室盆栽试验对水稻土CH4 排放的季节变化及冬作季节土地管理的影响进行了研究 .结果表明 ,冬作季节种植紫云英、淹水休闲及干燥休闲但泡水前施用稻草处理泡水后 3 0dCH4 排放量分别高达 13 3d观测期总排放量的 67.5 %、3 5 .5 %及 3 3 .3 % ,且在泡水后第 13天及水稻移栽后第 7、40、91天分别出现 4个CH4 排放高峰 ;而种植小麦和干燥休闲但冬作前施用稻草处理泡水后 5 5dCH4 排放量才占观测期总排放量的 6.74%和 0 .2 7% ,随后至水稻收获CH4 排放通量也不高 .冬作季节土地管理引起的水稻生长期土壤Eh季节变化的差异是造成CH4 排放通量季节变化差异的主要原因     

The significance of denitrification of applied nitrogen in fallow and cropped rice soils under different flooding regimes I. Greenhouse experimènts

The role of nitrification-denitrification in the loss of nitrogen from urea applied to puddled soils planted to rice and subjected to continuous and intermittent flooding was evaluated in three greenhouse pot studies. The loss of N via denitrification was estimated indirectly using the¹⁵N balance, after either first accounting for NH₃ volatilization or by analyzing the¹⁵N balance immediately before and after the soil was dried and reflooded. When urea was broadcast and incorporated the loss of¹⁵N from the soil-plant systems depended on the soil, being about 20%–25% for the silt loams and only 10%–12% for the clay. Ammonia volatilization accounted for an average 20% of the N applied in the silt loam. Denitrification losses could not account for more than 10% of the applied N in any of the continuously flooded soil-plant systems under study and were most likely less than 5%. Intermittent flooding of soil planted to rice did not increase the loss of N. Denitrification appeared to be an important loss mechanism in continuously flooded fallow soils, accounting for the loss of approximately 40% of the applied¹⁵N. Loss of¹⁵N was not appreciably enhanced in fallow soils undergoing intermittent flooding. Apparently, nitrate formed in oxidized zones in the soil was readily denitrified in the absence of plant roots. Extensive loss (66%) of¹⁵N-labeled nitrate was obtained when 100 mg/pot of nitrate-N was applied to the surface of nonflooded soil prior to reflooding. This result suggests that rice plants may not compete effectively with denitrifiers if large quantities of nitrate were to accumulate during intermittent dry periods.     

冬作季节土地管理对水稻土CH4排放季节变化的影响

通过温室盆栽试验对水稻土ＣＨ４排放的生节变化及冬作季节土地管理的影响进行了研究,结果表明,冬作季节种植紫云英、淹水休闲及干燥休闲但泡水前施用稻草处理泡水后３０ｄＣＨ４排放量分别高达１３３ｄ观测期总排放量的６７５％、３５．５％及３３．３％,且在泡水后第１３天及水稻移栽后第７、４０、９１天分别出现４个ＣＨ４排放高峰;而种植小麦和干燥休闲但冬作前施用稻草处理泡水后５５ｄＣＨ４排放量才占观测期总排放量的６     

冬作季节土地管理对水稻土CH4排放季节变化的影响

通过温室盆栽试验对水稻土CH₄ 排放的季节变化及冬作季节土地管理的影响进行了研究.结果表明,冬作季节种植紫云英、淹水休闲及干燥休闲但泡水前施用稻草处理泡水后30dCH₄ 排放量分别高达133d观测期总排放量的67.5%、35.5%及33.3%,且在泡水后第13天及水稻移栽后第 7、40、91天分别出现 4个CH₄ 排放高峰;而种植小麦和干燥休闲但冬作前施用稻草处理泡水后55dCH₄ 排放量才占观测期总排放量的6.74%和 0.27%,随后至水稻收获CH₄ 排放通量也不高.冬作季节土地管理引起的水稻生长期土壤Eh季节变化的差异是造成CH₄ 排放通量季节变化差异的主要原因.     

Phosphorus transformations from rock phosphates in acid soils and measures for increasing their efficiency for growing rice (Oryza sativa L.)

Summary Laboratory incubation experiments showed that addition of rock phosphate to P-deficient acid red and laterite soils resulted in an increase in Al–P or/and Fe–P, with a consequent decrease in Ca–P during 15 days, of moist aerobic incubation. The transformations of P from Gafsa, Jordan, North Carolina and Florida rock phosphates were more than those from Tennessee, Missouri and Udaipur. Studies with North Carolina, Gafsa, and Udaipur rock phosphates showed that application of the former two to moist aerobic P-deficient acid soils 2 weeks prior to flooding and transplanting rice gave higher content of Al–P, Fe–P and Bray-P, compared to when these were applied at flooding. The grain yields obtained with the former two treatments were also at par with that obtained with the addition of superphosphate at comparable rate (100 ppm) of P application, compared to when the, rock phosphates were applied at flooding, where the grain yields were lower than the superphosphate treatment, indicating that some of these rock phosphates could be made as efficient as superphosphate for growing rice on acid soils by their application to moist aerobic soil, 2–3 weeks prior to flooding and transplanting rice and thus conserve some amount of sulphur required for the manufacture of water soluble phosphates.     

Hydrologic Regime Controls Soil Phosphorus Fluxes in Restoration and Undisturbed Wetlands

Many wetland restoration projects occur on former agricultural soils that have a history of disturbance and fertilization, making them prone to phosphorus (P) release upon flooding. To study the relationship between P release and hydrologic regime, we collected soil cores from three restoration wetlands and three undisturbed wetlands around Upper Klamath Lake in southern Oregon, U.S.A. Soil cores were subjected to one of three hydrologic regimes—flooded, moist, and dry—for 7.5 weeks, and P fluxes were measured upon reflooding. Soils from restoration wetlands released P upon reflooding regardless of the hydrologic regime, with the greatest releases coming from soils that had been flooded or dried. Undisturbed wetland soils released P only after drying. Patterns in P release can be explained by a combination of physical and biological processes, including the release of iron‐bound P due to anoxia in the flooded treatment and the mineralization of organic P under aerobic conditions in the dry treatment. Higher rates of soil P release from restoration wetland soils, particularly under flooded conditions, were associated with higher total P concentrations compared with undisturbed wetland soils. We conclude that maintaining moist soil is the means to minimize P release from recently flooded wetland soils. Alternatively, prolonged flooding provides a means of liberating excess labile P from former agricultural soils while minimizing continued organic P mineralization and soil subsidence.     

Soil Texture and Cultivar Effects on Rice (Oryza sativa,L.) Grain Yield,Yield Components and Water Productivity in Three Water Regimes

The objective of this study was to determine the effects of water regime/soil condition (continuous flooding, saturated, and aerobic), cultivar (‘Cocodrie’ and ‘Rondo’), and soil texture (clay and sandy loam) on rice grain yield, yield components and water productivity using a greenhouse trial. Rice grain yield was significantly affected by soil texture and the interaction between water regime and cultivar. Significantly higher yield was obtained in continuous flooding than in aerobic and saturated soil conditions but the latter treatments were comparable to each other. For Rondo, its grain yield has decreased with soil water regimes in the order of continuous flooding, saturated and aerobic treatments. The rice grain yield in clay soil was 46% higher than in sandy loam soil averaged across cultivar and water regime. Compared to aerobic condition, saturated and continuous flooding treatments had greater panicle numbers. In addition, panicle number in clay soil was 25% higher than in sandy loam soil. The spikelet number of Cocodrie was 29% greater than that of Rondo, indicating that rice cultivar had greater effect on spikelet number than soil type and water management. Water productivity was significantly affected by the interaction of water regime and cultivar. Compared to sandy loam soil, clay soil was 25% higher in water productivity. Our results indicated that cultivar selection and soil texture are important factors in deciding what water management option to practice.     

Influence of draining on soil phosphorus forms and distribution in a constructed wetland

Seasonal water-table fluctuations in wetlands can result in flooded and drained conditions in the surface soil. In constructed wetlands water level drawdown and soil drainage are used in management to consolidate detrital materials, accelerate soil build up, and provide easy access for other management operations. A greenhouse study was conducted using intact peat soil cores to evaluate the changes in bioavailable P and other fractions following draining and reflooding. Measurements of floodwater dissolved reactive P (DRP) indicated that draining and soil exposure could result in large P flux to the overlying water column. Phosphorus flux in soils drained for 6 weeks was 10-fold higher (334 mg P m⁻² day⁻¹) than in soils drained for 3 weeks (33 mg P m⁻² day⁻¹). Soil exposure also resulted in an increase in bioavailable inorganic P (estimated by KCl extraction) at the expense of labile organic P pool. The KCl-P pool, which was initially less than 2% of total P (TP), increased to 3% and 13% of TP after 3 and 6 weeks draining, respectively. Results suggest that various soil P fractions, particularly those in newly accreted materials, were highly unstable and could be released in a more available form when newly accreted soils undergo drying. Water level drawdown and reflooding could result in significant P release, a possible stimulation of algal blooms and other water quality problems. Therefore, soil characteristics and chemistry and their impact on water quality should be a major consideration when one adopts the flood-drain technique in wetland management.     

The effects of flooding for rice culture on soil chemical properties and subsequent maize growth

Summary The effects of flooding and lowland rice culture on soil chemical properties and subsequent maize growth were investigated in two contrasting rice soils of S.E. Australia. The effects of incorporating rice straw, either during or after flooding were also studied. The experiment was conducted in a glasshouse with the use of large intact soil cores.Previous flooding markedly reduced maize growth, leaf P concentration and P uptake, despite the application of a large quantity of P fertilizer after drainage. Soil analyses showed that previous flooding increased the Langmuir sorption terms for maximum P sorption and bonding energy. The availability of P was more closely related to the bonding energy between soil and P than to the capacity of the soils to sorb P. The increases, in the P sorption parameters, were associated with decreases in the crystallinity of the free iron oxides as determined by their oxalate solubility. It was concluded that depressed P supply to maize sown in previously flooded soils was due to stronger P sorption by the drained soils, rather than to P immobilization during flooding.Rice plants grown during flooding reduced the amount of N available to the subsequent maize crop, but did not significantly affect P availability. Rice straw added during flooding did not affect subsequent maize growth, but when added after flooding caused microbial immobilization of N.Salts, Fe or Mn from previous flooding did not affect maize growth.     

Optimization of aquatic-terrestrial ecosystem in relation to soil nitrogen status for the cultivation of fish and aquatic food crops of the Indian subtropics

A case study was undertaken during wet and postwet seasons to improve the perennial and alternate submerged saucer-shaped ponded lands (tal and semi-tal lands) in the coasts and northeastern plains of the Indian subtropics through pisciculture and cultivation of starch- and protein-rich aquatic food crops like water chestnut (Trapa bispinosa Roxb.) and makhana or fox nut (Euryale ferox Salisb.). The study revealed that the physico-chemical properties of soils (pH, organic C, organic matter, available N, P, and K) as well as quality of water (pH, EC, BOD, COD, CO3 +, HCO3-, NO3-N, SO4-S-, and Cl-), growing fish, makhana, and water chestnut was remarkably influenced by different moisture regimes and exhibited a significant improvement of soil health. The amount of organic C, available N, P, and K content were found significantly highest in the treatment where makhana was grown under alternate flooding and drying situation with a depth >2 m as compared to other treatments. Such enrichment of soil fertility, particularly in available N and P content, might be due to the accumulation of considerable amounts of biomass and fish excreta and their subsequent decomposition in situ in the soils. Therefore, the present study suggests that the N-enriched soil may effectively be utilized further for growing subsequent arable crops surroundings during summer season, which not only saves the amount of applied N fertilizer but also increases the apparent N efficiency with simultaneous increase in yield, and would benefit the farmers in this region.     

Reducing greenhouse gas emissions,water use,and grain arsenic levels in rice systems

Agriculture is faced with the challenge of providing healthy food for a growing population at minimal environmental cost. Rice (Oryza sativa), the staple crop for the largest number of people on earth, is grown under flooded soil conditions and uses more water and has higher greenhouse gas (GHG) emissions than most crops. The objective of this study was to test the hypothesis that alternate wetting and drying (AWD – flooding the soil and then allowing to dry down before being reflooded) water management practices will maintain grain yields and concurrently reduce water use, greenhouse gas emissions and arsenic (As) levels in rice. Various treatments ranging in frequency and duration of AWD practices were evaluated at three locations over 2 years. Relative to the flooded control treatment and depending on the AWD treatment, yields were reduced by <1–13%; water‐use efficiency was improved by 18–63%, global warming potential (GWP of CH₄ and N₂O emissions) reduced by 45–90%, and grain As concentrations reduced by up to 64%. In general, as the severity of AWD increased by allowing the soil to dry out more between flood events, yields declined while the other benefits increased. The reduction in GWP was mostly attributed to a reduction in CH₄ emissions as changes in N₂O emissions were minimal among treatments. When AWD was practiced early in the growing season followed by flooding for remainder of season, similar yields as the flooded control were obtained but reduced water use (18%), GWP (45%) and yield‐scaled GWP (45%); although grain As concentrations were similar or higher. This highlights that multiple environmental benefits can be realized without sacrificing yield but there may be trade‐offs to consider. Importantly, adoption of these practices will require that they are economically attractive and can be adapted to field scales.     

Effect of Sesbania,Azolla and rice straw incorporation on the kinetics of NH4, K,Fe, Mn,Zn and P in some flooded rice soils

In a greenhouse study, with and without rice plants, of five flooded Philippine rice soils whose organic C (OC) content varied from 0.5 to 3.6%, incorporation ofSesbania rostrata, Azolla microphylla and rice straw affected the kinetics of soil solution NH ₄ ⁺ −N, K⁺, Fe²⁺, Mn²⁺, Zn²⁺, and P. Sesbania and Azolla increased NH ₄ ⁺ −N concentration above the control treatment, whereas rice straw depressed it. In all soils Azolla released less NH ₄ ⁺ −N than Sesbania. The apparent net N release depended on the soil and ranged from 44–81% for Sesbania and 27–52% for Azolla. These effects persisted throughout the growth of IR36. Soil solution and exchangeable NH ₄ ⁺ −N increased initially but levelled off between 30 to 80 days and between 20 to 40 days after flooding (DF), respectively. With rice, soil solution NH ₄ ⁺ −N concentration, reached a peak at 15–40 DF and declined to very low levels (<4mg L⁻¹). In the 3 soils of low OC content nitrogen derived from green manure ranged from 34–53% and the apparent revovery of added green manure N varied from 29–67%. Almost all N released from both Azolla and Sesbania were recovered in the rice plant in all soils except Concepcion with only 77%. The concentration of K⁺, Fe²⁺, Mn²⁺ and P in the soil solution were higher with rice straw than Sesbania and Azolla in all soils except Hanggan which showed no change in Fe²⁺ and Mn²⁺ but increased K⁺ and P. In general, rice straw, Sesbania and Azolla decreased Zn²⁺ concentration in all soils.     

Phosphorus nutrition of rice in relation to flooding and temporary loss of soil-water saturation in two lowland soils of Cambodia

In the rainfed lowlands, temporary loss of soil-water saturation during crop growth is a common factor limiting rice (Oryza sativa L.) yield but its effects on phosphorus (P) availability are poorly understood. Rice plants were transplanted into pots containing soils that were either continuously flooded, maintained at field capacity or flooded and then dried to field capacity for 3 weeks during the vegetative stage. A black clay soil (Kandic Plinthaquult) and a sandy soil (Plinthustalf) from south-east Cambodia were compared with or without amendments by rice straw and P fertilizer. Under continuously flooded conditions, the growth of rice was vigorous without straw addition and there was a strong response of rice growth to the addition of P fertilizer. The soil underwent reduction, which increased pH from 4.2 to 5.5 or 6.0, in the black clay or sandy soil, respectively. By contrast, a loss of soil-water saturation 3 weeks before panicle initiation (PI) markedly impaired the growth of rice. This was not through any effect of water stress, and the growth reductions were not as strong as with continued loss of soil-water saturation from transplanting to PI. Fluctuations in soil pH and Eh corresponded closely to changes in soil-water regimes. Growth reductions were attributed to reduced shoot P levels resulting from the decline in P availability during the loss of soil-water saturation. The addition of rice straw stimulated soil reduction and lessened changes in soil pH and Eh during the loss of soil-water saturation in both soils. Straw addition enhanced P uptake by the rice plants during loss of soil-water saturation, but its beneficial effects could not be attributed to the direct addition of P, N or K to the soils. Thus the application of rice straw may be effective in lessening the effects of temporary loss of soil-water saturation on rice growth in lowland rice soils by minimising the decline in P availability. This revised version was published online in August 2006 with corrections to the Cover Date.     

Maize response to intermittent submergence,straw mulching and supplemental N-fertilization in subtropical region

Summary A 2-year field study was undertaken on a sandy loam in a tropical monsoon region to determine the growth and yield response of maize (Zea mays L.) to 10–11 day intermittent submergence at two growth stagesviz., 20 (stage 1) and 40 (stage 2) days after planting, in combination with two rates of rice straw mulch (0 and 6 t/ha) and three levels (0, 30 and 60 kg/ha) of soil-applied supplemental nitrogen. Intermittent submergence at both growth stages caused a severe oxygen stress in the root-zone. Compared with no-flooding, stage-1 flooding without additional N reduced the grain yield by 51 and 69%, stover yield by 16 and 45% and grain: stover ratio by 41 and 47% in the first and second year, respectively. Similar were the submergence effects on N, P, K and Zn concentrations in leaves, ears per plant and grain weight per ear. Relatively more adverse effects of stage-1 flooding in the second than the first year followed from the hotter soil and atmospheric environments in the former season. The stage-2 flooding produced practically no ill effects on growth and yield of the crop. Soil application of 60 kg N/ha after termination of stage-1 flooding recovered the grain yield by 77% in the first year and 65% in the second year. Additional nitrogen also benefited the growth and yield characters. The interactive effects of straw mulching with flooding were not distinct. Senior Scientist (Irrigation), formerly graduate student and Assistant Soil Physicsts, respectively.     

Vermicompost as a soil supplement to improve growth, yield and fruit quality of tomato (Lycopersicum esculentum)

The effects of earthworm-processed sheep-manure (vermicompost) on the growth, productivity and chemical characteristics of tomatoes (Lycopersicum esculentum) (c.v. Rio Grande) were investigated in a greenhouse experiment. Five treatments were applied combining vermicompost and soil in proportions of 0:1, 1:1, 1:2, 1:3, 1:4 and 1:5 (v/v). Growth and yield parameters were measured 85 days and 100 days after transplanting. Addition of vermicompost increased plant heights significantly, but had no significant effect on the numbers of leaves or yields 85 days after transplanting. Yields of tomatoes were significantly greater when the relationship vermicompost:soil was 1:1, 1:2 or 1:3, 100 days after transplanting. Addition of sheep-manure vermicompost decreased soil pH, titratable acidity and increased soluble and insoluble solids, in tomato fruits compared to those harvested from plants cultivated in unamended soil. Sheep-manure vermicompost as a soil supplement increased tomato yields and soluble, insoluble solids and carbohydrate concentrations.