Unmulched Conditions Research Articles

Effects of meteorological variables on potato leaf roll virus and potato virus y infections on different potato varieties under natural and mulched conditions

After rice and wheat, potatoes are the third most important staple crop in Pakistan, but due to various virus diseases attacks, yield remains very low. Among viral pathogens, potato leaf roll virus (PLRV) and potato virus Y (PVY) are the most destructive viruses present in all potato-growing areas. A field experiment was conducted at the Research Farm of Plant Virology Section, Ayub Agricultural Research Institute, Faisalabad, to evaluate the effects of meteorological variables on the development of virus infections (PLRV and PVY) on different potato varieties under natural and mulched conditions. Results indicated that the development of infections of PVY and PLRV was delayed in different potato varieties under mulched conditions. The potato variety Simply Red had the highest PLRV and PVY disease incidences under unmulched and mulched circumstances, while Sahiwal Red and Ruby had the lowest infection rates. The least PVY disease incidence was noted under mulched conditions on FD-81-1. Mulched conditions were better in the reduction of diseases than unmulched conditions. The average high temperature (HT) ranged from 21.9 ◦C to 27 ◦C was most favorable for the development of PLRV and PVY on all six tested potato varieties in both conditions. The average low temperature (LT) ranged from 8 ◦C to 15 ◦C was favorable for the progression of PLRV and PVY diseases in both conditions. The relative humidity (RH) range of 50-60% was conducive for the development of PLRV and PVY diseases. It is concluded that mulching application is an essential tool to enhance the yield of potato crops by reducing their specific diseases.

Influence of different organic mulches on soil hydrothermal and plant growth parameters in potato crop (Solanum tuberosum L.)

Present study was conducted to investigate the effect of different mulching materials on soil hydrothermal environment and plant growth parameters for potato crop at field experimental station of National Institute of Technology, Hamirpur in the humid sub-tropical agro climate of Western Himalayas. The field experiments were conducted in a randomized complete block design with four mulching treatments; wheat straw mulch, pine needle mulch, rice straw mulch and no mulch in three replications. An increase in soil moisture retention ranging from 5.14% to 42% was observed depending upon the mulch material and depth of the soil layer in root zone. Mulching also reduced the daily maximum soil temperature up to 3.5ºC with an average temperature reduction of 1-2ºC during the period of tuber formation. Mulching produced beneficial effects on root depth, plant height, leaf area index and tuber yield. Mulching helped to bring about a yield surplus of 1.7-4.4 tonnes ha-1 over unmulched conditions and an increase in water use efficiency which varied from 13.5% in rice straw mulch to 34.9 % inwheat straw mulch.

Effect of Planting Depth and Mulching Materials on Yield and Yield Attributes of Potato in Dadeldhura, Nepal

Potato, a staple crop for hill and mountainous region has significant contribution in maintaining food and nutrition security. It alone shares around 2.17% of Gross Domestic Product. With phenomenal climate change, pest and disease are increased, hills are and mountains are getting dried leading to moisture deficit which in turn are decreasing the yield of potato. So, with this existing trouble this study has focused to discover innovation in major two agronomic practices: planting depth and mulching. But, the farmer of Nepal often uses haphazard planting depth and mulching which contribute to the low yield. Thus, in order to study, its effect on planting depth and mulching, a research was conducted in the Dadeldhura district of Nepal in 2019. The research was carried out in factorial 2×3 Randomized Complete Block Design which consist of mulch and un-mulched condition as 1^st factor and three different planting depth of (10cm, 15cm and 20cm) as 2^nd factor. So altogether there are six treatments with four replications. Data were collected on growth, tuber yield and quality parameter and analyzed using R-studio software. Regarding 1^st factor, mulched treatment was found significantly superior than un-mulched treatment in case of all yield attributes like plant height, stem number, canopy and leaves number. Total tuber yield was found 3.626 kg/m² in mulch treatment which was highly significant (P<0.01). In case of 2^nd factor, tuber planted at a depth of 15cm produced maximum number of aerial stem per plant 5.2 (P<0.001) number of large size tuber per plant 9.025 (P<0.01) and tuber yield 3.82kg/m² (P<0.01) as compared to other planting depth of 10cm and 20cm. There was no any significant difference in case of interaction between the two factors. Therefore, it can be concluded from the result that with the use of mulching and planting depth of 15cm all yield attributes and yield of potato was found to be superior under the climatic condition of Dadeldhura, Nepal.

Effect of Planting Depth and Mulching Materials on Yield and Yield Attributes of Potato in Dadeldhura, Nepal

Potato, a staple crop for hill and mountainous region has significant contribution in maintaining food and nutrition security. It alone shares around 2.17% of Gross Domestic Product. With phenomenal climate change, pest and disease are increased, hills are and mountains are getting dried leading to moisture deficit which in turn are decreasing the yield of potato. So, with this existing trouble this study has focused to discover innovation in major two agronomic practices: planting depth and mulching. But, the farmer of Nepal often uses haphazard planting depth and mulching which contribute to the low yield. Thus, in order to study, its effect on planting depth and mulching, a research was conducted in the Dadeldhura district of Nepal in 2019. The research was carried out in factorial 2×3 Randomized Complete Block Design which consist of mulch and un-mulched condition as 1st factor and three different planting depth of (10cm, 15cm and 20cm) as 2nd factor. So altogether there are six treatments with four replications. Data were collected on growth, tuber yield and quality parameter and analyzed using R-studio software. Regarding 1st factor, mulched treatment was found significantly superior than un-mulched treatment in case of all yield attributes like plant height, stem number, canopy and leaves number. Total tuber yield was found 3.626 kg/m2 in mulch treatment which was highly significant (P<0.01). In case of 2nd factor, tuber planted at a depth of 15cm produced maximum number of aerial stem per plant 5.2 (P<0.001) number of large size tuber per plant 9.025 (P<0.01) and tuber yield 3.82kg/m2 (P<0.01) as compared to other planting depth of 10cm and 20cm. There was no any significant difference in case of interaction between the two factors. Therefore, it can be concluded from the result that with the use of mulching and planting depth of 15cm all yield attributes and yield of potato was found to be superior under the climatic condition of Dadeldhura, Nepal.

EFFECT OF DIFFERENT FERTILIZERS IN YIELD AND NODULATION OF COWPEA (VIGNA UNGUICULATA) UNDER MULCHED AND UN-MULCHED FIELD CONDITION IN CHITWAN DISTRICT, NEPAL

To study the effects on nodulation and yield of Cowpea (Vigna Unguiculata), a research had been conducted in the sandy loam soil of the horticulture farm of Agriculture and Forestry University in 2018. The experiment was laid out in factorial 2×5 Randomized complete block design with ten treatments and 3 replications which consists; 1st factor – mulched and un-mulched condition, 2nd factor – Rhizobium inoculation (R) at 1gm/ 16.66 gm seed, Phosphorus (P) at recommended dose of 120kg/ha ,use of R plus P(RP),RP plus Molybdenum (RPMo) at 2 gm Molybdenum per kg seed and control with no such application. The analysis of the findings showed that mulched and RPMo treatment were found significantly superior than other treatments in case of main effects of yield attributes like plant height, canopy diameter and stem number. The highest fresh weight of pods per plant i.e. 312.61 gm and 312.53 gm and no of nodules per plant i.e. 121.63 and 129.33 were found in mulched and RPMo treatment, significant at p

Irrigation water quality and mulching effects on tuber yield and soil properties in potato (Solanum tuberosum L.) under semi-arid conditions of Indian Punjab

A field experiment was conducted for 5 years from 2009 to 2015 at Punjab Agricultural University Regional Research Station, Bathinda, Punjab, India to observe the effect of irrigation water quality on tuber yield, soil characteristics and water productivity of potato under mulched conditions in light textured soil under semi arid climate of Indian Punjab. The experiment was conducted in split plot design with three mulch treatments viz. no mulch (M0), rice straw mulch @ 6 t ha−1 (Ms) and polyethylene mulch, black 50 μm (Mp) in main plots and three irrigation water qualities viz. canal water alone (CW), poor quality saline-sodic ground water alone (GW) and cyclic use of CW and GW (CW-GW) in sub plots. The experimental soil was alkaline in reaction, low in organic carbon, medium in available phosphorus and high in available potassium. The electrical conductivity (EC) and residual sodium carbonate (RSC) of canal water and ground water was 0.45 dS m−1, -0.6 mmolc L−1; and 2.2 dS m−1, 6.44 mmolc L−1, respectively. The results revealed that under unmulched conditions (M0), CW and CW- GW gave significantly higher tuber yield than GW. Mulching, in general, resulted in significantly higher marketable tuber yield than in non mulched conditions. The tuber yield was statistically at par with Ms and Mp, irrespective of the irrigation water quality. Similar trends were observed in case of yield attributing parameters viz. plant height, number of haulms per plant and number of marketable tubers per plant. The water use efficiency was higher under Ms and Mp than under M0. The highest water use efficiency was recorded in Ms under CW irrigation. Among the quality parameters, dry matter and total sugars increased with application of saline-sodic GW as compared to CW-GW and CW irrigation due to higher abiotic stress due to salts.

Response of different colour plastic mulches on water dynamics under drip fertigated greenhouse capsicum (Capsicum annuum)

The study analyses spatio-temporal distribution of soil moisture pattern under colored plastic mulches inside the ventilated greenhouse. The experiment was conducted at Centre for Protected Cultivation Technology, Indian Agricultural Research Institute, New Delhi. Water distribution in the root zone of capsicum (Capsicum annuum L.) was simulated for three colored plastic mulches (silver, yellow and black) and unmulched condition (control) with three level of irrigation (100% ETc, 80% ETc and 60% ETc). It was found that for two levels of irrigation (100% and 80% ETc) highest yield was obtained, so for these two irrigation levels simulation of water dynamics was done by the Hydrus-2D model. The irrigation cycle was 72 h (i.e. 3 days) and indicates that moisture was readily available in the vicinity of root zone. Simulation study showed that water content for sandy loam soil was more in the second layer of soil (15 to 30 cm) and was near the field capacity. The R2-value obtained for silver plastic mulch at 100% of ETc was highest (0.91 to 0.94) and the second highest R2-value is for yellow plastic mulch at 80% of ETc (0.89 to 0.91). The results showed that at 100% of ETc, silver color mulch has comparatively more water content than other treatments. Simulation studies showed that silver plastic mulch optimised the water content in the vicinity of capsicum root zone for 1 lh-1 dripper discharge. So, silver plastic mulch was efficiently utilized, as the capsicum root zone was found within 20 to 30 cm depth. This indicates that the Hydrus-2D can be used effectively for predicting soil moisture distribution covered with plastic mulch.

Impact of carbonates on the mineralisation of surface soil organic carbon in response to shift in tillage practice

The inorganic soil C pool is a major source of CO2 emission into the atmosphere along with the soil respiratory CO2 fluxes but is comparatively less studied than the organic C mineralisation processes. This study aims to understand how soil available carbonates influence the soil C dynamics under different tillage, mulching and temperature regimes. A 90-day incubation experiment was conducted by adding calcite nodules to soils (10% w/w) collected from an agricultural field maintained with or without 5 t ha−1 mulching under no-till (NT) or conventional tillage (CT) systems. Environmental Scanning Electron Microscope (ESEM) examination indicated greater morphological changes in the calcite nodules incubated with CT than NT soils. Soil samples incubated with calcite and mulching recorded 6.3% greater CO2 evolution than the un-mulched condition. Under the CT system, the overall CO2 emission rate was higher in the control treatment (43%), followed by a combined treatment of 5 t ha−1 mulch + CaCO3 (10% w/w) (29.2%), 5 t ha−1 mulch only treatment (27.9%), and 10% CaCO3 (w/w) (16.5%) treatment, with a rise in incubation temperature from 22 °C to 37 °C. Kinetic model calculations for CO2 emission indicated a greater half-life of easily mineralisable C pools in the NT system at 22 °C. Microbial biomass carbon (MBC) results further verified that the high temperature and disturbed soil conditions limit the availability of soil MBC under the CT systems, indicating a higher decomposition rate. Eventually, these results indicated that agricultural management practices, including tillage shift, explicitly influence the different functional components of soil organic matter (SOM).

Effect of Rhizobium Inoculation, Phosphorus and Molybdenum in Yield, Yield Attributes and Nodulation of Cowpea under Mulched and Un-Mulched Field Condition

Cowpea is an important source of nutrition being popular in Nepal. In order to study its effect on nodulation, yield and yield attributes, a research was conducted in the sandy loam soil of the horticulture farm of Agriculture and Forestry University in 2018. The experiment was laid out in factorial 2×5 RCBD which consists of mulched and un-mulched condition as 1st factor and rhizobium inoculation (R) at 1gm/ 16.66 gm seed, phosphorus (P) at recommended dose of 120kg/ha, use of R plus P (RP), RP plus Molybdenum (RPMo) at 2 gm per kg seed and control with no such application as 2nd factor. So altogether there are ten treatments with three replications. Regarding 1st factor, mulched treatment was found significantly superior than un-mulched treatment in case of all yield attributes like canopy, stem diameter and plant height. Yield and no of nodules per plant was found 312.61 gm and 121.63 respectively in mulched treatment which was highly significant (P < 0.001) than un-mulched. In case of 2nd factor, plant height at 60 days after sowing was found significantly superior in all applications than control. Yield and no of nodules per plant was found 312.53gm (P < 0.01) and 129.33 (P < 0.05) respectively in RPMo treatment which was statistically significant and at par with P, RP and R treatment respectively and lowest in control. The rise in number of nodules due to the different treatment applications had the high positive correlation (P < 0.01) with yield and yield attributes. There was no any significant interaction between the two factors. Use of mulching and RPMo treatment was found to be the most suitable combination for cowpea in sandy loam soil.

Effect of fertigation, splitting and mulching on different fruit crops

Fertigation, splitting and mulching are an essential tools in precision farming and that effectively affected in physiological, growth attributes, yield and quality parameters as well as nutrients content in leaves. Joint use of fertigation and mulch resulted in comparable growth and yield as unmulched condition and saved in fertilizers and irrigation water. Mulches maintain the soil temperature, retard the loss of soil moisture, suppress of wood growth, conservation of soil from erosion, reduction of soil salinity, improvement of soil structures, improve water infiltration rate by creating hindrance in flow of water, control of pest and diseases and enhance microbial activity in the field. The total dry matter (TDM) production and leaf area index were significantly higher in drip irrigation. Water-soluble fertilizer (WSF) fertigation recorded significantly higher total dry matter and LAI over drip irrigation. Chlorophyll concentration was significantly higher in fertigation treatments over soil applied treatments. The fruit yield in fruit crop was higher in drip irrigation over furrow irrigation. Fertigation with 100 per cent WSF increased the fruit yield significantly over furrow-irrigated control and drip irrigation. Fertigation resulted in lesser leaching of NO 3 -N and K to deeper layer of soil. Subsurface drip fertigation caused higher assimilable P in deeper layer.

Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

Purple soil is widely distributed in the hilly areas of the Sichuan basin, southwest China, and is highly susceptible to water erosion. The triggering of this process is related to slope, rainfall intensity and surface cover. Therefore, this study assesses the effects of different simulated rainfall intensities with different slopes on hydrological and erosional processes in un-mulched and mulched purple soils. Results show that the sediment and water losses increased with an increase of rainfall intensity and slope steepness. Generally, the slope contribution (Sc) on water and sediment losses decreased with increasing rainfall intensity and slope steepness under both un-mulched and mulched soil. In un-mulched conditions, water losses were independent of slope steepness (Sc &lt; 50%) during the highest rainfall intensity. However, in mulched soil, the higher contributions of slope (Sc) and rainfall (Rc) were found for water and sediment losses, respectively, i.e., &gt;50%, except during the increase in slope steepness from 15° to 25° under the highest rainfall intensity (120 mm·h−1). The effectiveness of mulch was more pronounced in reducing sediment losses (81%–100%) compared with water losses (14%–100%). The conservation effectiveness of mulch both decreased and increased with slope steepness for water and sediment losses, respectively, under higher rainfall intensities. Water infiltration and recharge coefficient (RC) decreased with an increase of slope steepness, while with an increase in rainfall intensity, the water infiltration and RC were increased and decreased, respectively, in both un-mulched and mulched soil. On the other hand, mulched soil maintained a significantly (α = 0.05) higher infiltration capacity and RC compared to that of the un-mulched soil.

Effect of Drip Fertigation With and Without Mulch on Soil Hydrothermal Regimes, Growth, Yield, and Quality of Apple (Malus domestica Borkh)

Studies were undertaken to investigate the effect of drip fertigation and conventional fertilizations with and without mulch on the productivity of apple. Soil moisture under fertigation remained greater in the upper 0–30 cm of soil, whereas under conventional surface irrigation, deeper layers registered greater values. Mulch application resulted in 2–4% greater moisture and raised the minimum but lowered the maximum soil temperatures, especially during later growth periods. Available nitrogen (N) and potassium (K) contents under fertigation closely followed the moisture distribution pattern. Irrespective of treatments, available phosphorus (P) remained confined within upper 0- to 20-cm soil depth. Fertigation resulted in 35% greater growth and yield over conventional fertilization with irrigations besides saving 25% in irrigation water. Joint use of fertigation and mulch resulted in comparable growth and yield as unmulched condition and saved 20% in fertilizers and 15% in irrigation water.

Interactive effect of tillage depth and mulch on soil temperature, productivity and water use pattern of rainfed barley ( Hordium vulgare L.)

Soil porosity and organic matter content influence the hydrology, thermal status and productivity of agricultural soils. Shape, size and continuity of soil pores are determined by tillage practices. Thus appropriate tillage and mulch management can conserve residual soil moisture during the post rainy season. This can play a key role in enhancing productivity under the rainfed ecosystem of subhumid region in eastern India. A field study was carried out on a fine loamy soil from 1993–1994 to 1995–1996. Two tillage treatments were conventional ploughing (150 mm depth) and shallow ploughing (90 mm) depth. Each tillage practice was tested with three mulch management viz., no mulch, soil dust mulch and rice ( Oryza sativa L.) straw mulch. Soil organic carbon, bulk density, moisture retentivity, soil temperature with productivity and water use pattern of barley ( Hordium vulgare L.) were measured. Reduction in ploughing depth resulted in nominal increase in profile (0.0–1.2 m) moisture status, yield, and soil thermal status at 14:00 and water use efficiency (WUE). However, it decreased the magnitude of soil temperature in the morning (07:00). Straw mulch conserved 19–21 mm of moisture in the profile (1.2 m) over the unmulched condition. Both soil dust and rice straw mulching elevated soil thermal status at 07:00 as compared to unmulched condition, but this trend was reversed at 14:00. Straw mulching significantly increased grain yield and WUE over soil dust mulch and unmulched condition. Impact of straw mulch was more pronounced under shallow ploughing depth. Shallow tillage with rice straw mulching is recommended to the farmers to obtain higher level of yield and water use efficiency.

Tree-crop interactions in hedgerow intercropping with different tree species and tea in Sri Lanka: 2. Soil and plant nutrients

The primary objective of the present study was to determine the capacity for soil fertility improvement in hedgerow intercropping systems (HIs) involving six different hedgerow species (Calliandra calothyrsus Meissner, Senna [Cassia] spectabilis (DC.) H. Irwin and Barneby, Euphatorium innulifolium (R.M. King and H. Rob.) H.B.K., Flemingia congesta Aiton F., Gliricidia sepium (Jacq.) (Kunth.) Walp. and Tithonia diversifolia (Hemsl.) A. Gray) and tea (Camellia sinensis (L.) O. Kuntz) on sloping terrain in the high rainfall zones of Sri Lanka. Incorporation of hedgerows and addition of their prunings as mulch decreased topsoil bulk density and increased organic matter content and cation exchange capacity. In the majority of mulched HIs, most of the essential soil nutrients, with the exception of phosphorus, were higher than in sole tea crops. In HIs involving all tree species, the mulched treatment had significantly greater soil nutrient contents than the respective unmulched treatment. When prunings were not added as mulch, there was evidence of competition for nutrients between the tea bushes and hedgerow species. The amounts of nutrients added through hedgerow prunings exceeded the recommended K requirement of tea, but were lower than the N and P requirements. In a majority of HIs, the amounts of nutrients exported as tea yield were lower than in the control under both mulched and unmulched conditions. It is concluded that incorporation of contour hedgerows has the potential to regenerate soil fertility and sustain tea yields on sloping terrain in Sri Lanka, when prunings are added as mulch.

Performance of winter groundnut (Arachis hypogaea) with polythene mulch under rainfed condition of Manipur valley

A field experiment was conducted during the winter season 1997 98 and 1998 99 at Manipur centre, Lamphelpat Farm, Imphal, to study performance of groundnut (Arachis hypogaea L.) as rainfed crop under polythene mulch in broad bed furrow (BBF) and flat bed system of sowing. Higher production potential of JL 24 groundnut (1,602 kg and 2J80.7 kg pod yieldlha) was recorded with polymulch over unmulched condition (875 kg and 1,063 kg pod yieldlha). The vegetative and reproductive phases also differed under mulched and unmulched conditions. Germination was recorded 10 12 days earlier while maturity delayed by 15 20 days under polythene mulch. Number of branches/ plant, dry matter accumulationlplant, pod weight and 100 kernel weight were found significantly higher under polymulched condition than unmulched condition.

Field‐Grown Tomato Response to Carbonated Water Application

AbstractDirect release of CO2 gas to achieve a cost‐effective method of atmospheric CO2 enrichment has not been proven feasible under field conditions. We hypothesized that greater efficiency of application would occur by applying CO2 via carbonated water and that application would also result in beneficial modifications of the soil environment. Our objectives were to evaluate crop, soil, and atmospheric CO2 responses to application of carbonated water under pressure through a drip irrigation system. Studies were conducted under mulched and unmulched conditions in 1988 using tomato (Lycopersicon esculentum Mill.). In 1989, carbonated water was applied at approximately 2‐, 4‐, and 6‐d intervals to determine the effect of irrigation frequency. In 1988, a positive yield response of 9% was obtained in the presence of mulch. No response was observed in open beds. Fruit yields were increased at all three irrigation frequencies in 1989, with increases in fresh‐market and total fruit yields averaging 16.4 and 15.9%, respectively. Atmospheric enrichment was observed during carbonated water application, but residual enrichment between irrigations was difficult to detect. Significant increase in soil‐air CO2 from carbonated water application was noted throughout the intervals between successive irrigation events. Carbonated water application also decreased soil pH for periods of up to 5 d after irrigation and increased apparent uptake of P, K, Ca, Mg, Zn, Fe, Mn, Cu, and B. Based on the limited duration of enrichment relative to the entire growing season for any of the carbonated water treatments, the yield responses observed could not be attributed solely to atmospheric enrichment. Thus, we conclude that yield increases resulted from the combined effects of limited atmospheric CO2 enrichment and soil environment modifications leading to improved nutrient uptake.

Cotton Canopy and Drying Effects on Runoff During Irrigation with Moving Sprinkler Systems

AbstractSelf‐propelled moving sprinkler irrigation systems (MSIS) have become increasingly popular in recent years. However, high amounts of runoff were measured from fields during irrigation with MSIS. Surface runoff from a silt loam loess soil (Calcic Haploxeralf) and a clay vertisol soil (Typic Chromoxerert) under different irrigation management was studied in field plots (3 m2, with a slope of about 2%). The experimental fields were irrigated with a lateral MSIS (spray nozzle) with a discharge of 650 L m−1 h−1 and an average water application rate of about 100 mm h−1. The percent surface runoff in loess and vertisol soils was 22 and 0%, respectively, under straw mulch conditions vs. 53 and 39% under unmulched conditions. The greater runoff was due mainly to crust formation at the soil surface. The impact energy of the irrigation water drops caused the soil surface structure to break down and form a surface crust with a resultant decrease in the infiltration rate (IR). Coverage of the loess‐crusted soil surface by the cotton (Gossypium hirsutum L., cv. Acala SJ‐2) canopy did not reduce the percent runoff from weekly irrigations of 50 mm. A drying period of 7 d between water applications did not break the crust, which was formed at the beginning of the irrigation season, and the large amount of runoff (50%) remained constant until the end of the season. Conversely, 14 to 18 d of drying caused a breakage of the crust, resulting in increased IR. Under these conditions, the cotton canopy prevented the reformation of the crust during consecutive irrigations and the runoff decreased to 15% at the end of the season. When the amount of water per irrigation was 15 to 30 mm and the drying period was 2 to 3 d, the runoff value was about 20%. This low percentage apparently resulted from insufficient amounts of water necessary to form a fully developed crust.

The use of polyethylene mulches to change soil microclimate as revealed by enzyme activity and biomass nitrogen, sulphur and phosphorus

The effects of white, black and clear polyethylene mulches on temporal fluctuations in protease, sulphatase and phosphatase activities and levels of available and biomass N, S and P in raised beds of soil under a strawberry crop were investigated under field conditions. During spring, summer and early autumn, clear and, to a lesser extent black, polyethylene mulch increased both maximum and minimum mean monthly temperatures over those recorded with white mulch or no mulch. During summer and autumn, soil moisture content measured at monthly intervals was higher under mulched than unmulched conditions. Levels of extractable nitrate and sulphate in soils during autumn followed the order: clear mulch = black mulch > white mulch > no mulch. However, there were no significant differences in levels of enzyme activity or concentrations of biomass N, S or P between treatments. There were significant seasonal fluctuations in estimates of biomass N, S and P, but there was no close relationship between fluctuations in any estimate. This discrepancy was attributed to errors in the chloroform fumigation technique. Enzyme activities showed significant temporal fluctuations but the three enzymes did not show similar times of minimum and maximum activity. The complexity of interactions between soil microbial and biochemical properties and nutrient availability was exemplified by the absence of a discernible relationship between seasonal fluctuations in enzyme activities and levels of biomass N, S and P and/or levels of extractable mineral N, S and P in the soil. Strawberry fruit yields and vegetative growth followed the order : clear mulch = black mulch>white mulch>no mulch. Clear, and to a lesser extent black mulch increased the percentage of total yields produced in the first 2 months of cropping.

Effect of polyethylene mulch on soil temperature variation under planted greenhouse in aridic region

An analysis of the effect of mulch on soil temperature under tomato plants grown in a greenhouse is presented. Under greenhouse conditions, the soil temperature differences under mulched and unmulched conditions are found to be significant within the first 20 cm of the soil depth. The decrease of maximum soil temperature at day (2–3°C) and the increase of the minimum at night (2.0–3.5°C) compared with the unmulched is due to mulch. The polyethylene mulch damps the diurnal wave of soil surface temperature. The diurnal variation over soil surface for mulched soil was confined between 12–16°C, while under unmulched soil was between 11.5–19.5°C. The seasonal variation of the soil temperature is discussed. Shape differences between both treatments for hourly soil temperature are illustrated.

Effect of mulch on soil temperature in humid tropical latosols under coconut ( Cocos nucifera Linn.) and banana ( Musa paradisiaca)

An analysis of the effect of mulch on soil temperature in humid tropical latosols under coconut ( Cocos nucifera Linn) and banana ( Musa paradisiaca) is presented. Under both coconut and banana the soil temperature differences under mulched and unmulched conditions are found to be significant within the first 10cm of soil depth. The decrease of soil temperature due to mulch was 2–6°C under coconut, and 1–6°C under banana in surface depths of 5–10 cm. The diurnal variation over these surface depths for mulched plots was confined between 30 and 33°C under both coconut and banana, while a maximum of 40°C was observed for unmulched plots under coconut. The seasonal variation of soil and air temperature within a short period of 3 weeks is discussed. The surface (5 cm) soil temperature decreases from 38 to 27°C with the onset of rains.