Wet Tillage Research Articles

Optimizing dry and wet tillage for rice on a Gangetic alluvial soil: Effect on soil characteristics, water use efficiency and productivity of the rice–wheat system

The effect of puddling in reducing water and nitrogen losses, and increasing rice (Oryza sativa L.) yields and N uptake depends on its intensity and also on the level of pre-puddling tillage, although an increase in the intensity of these operations involves excessive energy and may lead to a negative effect on the yield of succeeding wheat (Triticum aestivum L.) due to sub-soil compaction. A 3-year field experiment was conducted on a sandy loam (Typic Ustochrept) soil of Modipuram, India to study the interactive effects of pre-puddling tillage and puddling intensity on irrigation water productivity (IWP) in rice, the concentration of nitrate-N in the soil profile, and the performance of rice and wheat crops. Treatments included 3 levels of pre-puddling tillage – discing followed by a tine-cultivation and planking (T1), discing followed by 2 tine-cultivations and planking (T2), or discing followed by 4 tine-cultivations and planking (T4); and 3 puddling intensities, i.e. 1, 2 or 4 passess of a puddler in ponded water (P1, P2 and P4, respectively), each followed by planking. Increasing tillage levels from T1P1 to T4P4 decreased irrigation water requirement by 22–25%, and increased rice grain yield by 1.6–2.2tha−1 and IWP by 0.26–0.34kgm−3 in different years. The post-rice nitrate-N concentration in the soil further indicated the advantage of puddling in retaining more nitrate-N in the upper profile, i.e. effective root zone. There was a significant (p≤0.05) interaction between pre-puddling tillage and puddling intensity on puddling index, which was the highest (0.63–0.65) under T4P4 during all years. Treatment T4P4 also increased bulk density over T1P1, especially at 28–33cm depth. This sub-soil compaction led to decreased wheat root mass density and wheat grain yield; the adverse effect of excessive puddling on wheat yield increased with time. The present study indicated 2 pre-puddling tillage operations followed by 2 passes of puddler, i.e. T2P2 as the optimum tillage combination with respect to energy efficiency in rice, total annual productivity and economic returns of the rice–wheat system.

Evaluation of precision land leveling and double zero-till systems in the rice–wheat rotation: Water use, productivity, profitability and soil physical properties

In recent years conventional production technologies in the rice–wheat (RW) system have been leading to deterioration of soil health and declining farm profitability due to high inputs of water and labour. Conservation agriculture (CA)-based resource-conserving technologies (RCTs) vis-à-vis zero-till (ZT), raised-bed planting and direct-seeded rice (DSR) have shown promise as alternatives to conventional production technologies to overcome these problems. The integration of CA-based RCTs with precision agriculture (PA)-based technologies in a systems perspective could provide a better option for sustainable RW production systems. In this study we attempted to evaluate conservation and precision agriculture (CPA)-based RCTs as a double-ZT system integrated with laser-assisted precision land leveling (PLL) in the RW system. A field experiment was conducted in the western IGP for 2 years to evaluate various tillage and crop establishment methods under PLL and traditional land leveling (TLL) practices to improve water productivity, economic profitability and soil physical quality. Irrespective of tillage and crop establishment methods (TCE), PLL improved RW system productivity by 7.4% in year 2 as compared to traditional land leveling. Total irrigation water savings under PLL versus TLL were 12–14% in rice and 10–13% in wheat. PLL improved RW system profitability by US$113 ha −1 (year 1) to $175 ha −1 (year 2). Yields were higher in conventionally transplanted rice followed by direct-drill-seeded rice after ZT. In wheat, yields were higher in ZT when followed by DSR than in the conventional-till (CT) system. RW system productivity under double ZT was equivalent to that of the conventional method. Among different TCE, conventional puddled-transplanted rice-CT wheat required 12–33% more water than other TCE techniques. Compared with CT systems, double ZT consumed 12–20% less water with almost equal system productivity and demonstrated higher water productivity. The CT system had higher bulk density and penetration resistance in 10–15 and 15–20 cm soil layers due to compaction caused by the repeated wet tillage in rice. The steady-state infiltration rate and soil aggregation (>0.25 mm) were higher under permanent beds and double ZT and lower in the CT system. Under CT, soil aggregation was static across seasons, whereas it improved under double no-till and permanent beds. Similarly, mean weight diameter of aggregates was higher under double ZT and permanent beds and increased over time. The study reveals that to sustain the RW system, CPA-based RCTs could be more viable options: however, the long-term effects of these alternative technologies need to be studied under varying agro-ecologies.

Effect of puddling intensity on physical properties of a silty clay soil under laboratory and field conditions

Conventional tillage and planting method for rice (Oryza sativa L.) production in northern Iran is wet tillage (puddling). Effect of different puddling intensities on physical properties of a silty clay soil (Typic Haplodalfs) was investigated under laboratory and field conditions. Changes in soil physical parameters and water requirement for puddling were measured. For laboratory experiments, undisturbed cylindrical soil samples (diameter and height of 50 cm), were used. A laboratory puddling apparatus was designed and constructed. The puddling intensity was measured by duration of puddling. Four levels of puddling intensity were used as: P0 (no puddling, control), P1 (low), P2 (medium) and P3 (high). For field tests, 12 plots of 8 × 4 m were selected. The first tillage was performed with a moldboard plow and then the plots were puddled with different intensity using a rotary tiller. The results showed that under laboratory conditions, water content of the puddled layers decreased with an increase in settling time. During drying period, P0 dried faster than P1, P2 and P3. Puddling with low intensity in laboratory and field conditions caused bulk density of 0–15 cm soil layer to decrease by 24.07 and 25.45%, respectively. Increasing puddling intensity increased the bulk density. Bulk density increased with time as particles settled after halting the puddling. Bulk density increased with depth as well. Under laboratory conditions, increasing puddling intensity from P1 to P2 reduced percolation rate significantly. For all puddling intensities, soil moisture characteristic curves of both field and laboratory samples showed that puddling increased the amount of water retained over the whole range of suctions. More water was needed for P3 as compared to P1 and P2. Under the laboratory and field conditions, the P3 required 27.72 and 28.58% more water as compared to P2, respectively. Although the mechanisms implemented for puddling were different under laboratory and field experiments, the results were similar. Bulk density, soil moisture content and water percolation rate decreased faster in the puddled soil under field and laboratory conditions. Therefore, to reduce the cost and time, the laboratory method could be used to study the effects of puddling intensity on physical properties of paddy soils. Medium intensity puddling was shown to be the proper tillage practice for paddy fields with silty clay soil.

Comparison of compaction and puddling as pre-planting soil preparation for mechanized rice transplanting in very gravelly Calcisols in central Iran

The conventional method of tillage and planting for rice ( Oryza sativa L.) production in central Iran is wet tillage (puddling) and manual transplanting. In this region, four-wheel (two-wheel drive) tractors are commonly used as the power unit for the puddling operation. The sinkage of tractor wheels during the puddling may deepen the hardpan layer and would create problems if mechanical transplanting was adopted due to the difficulty of the traction wheels moving through the puddled soil. Due to the shortage of irrigation water and increasing labour cost in recent years, researchers are seeking alternative soil management that would reduce water requirement and facilitate mechanisation of rice transplanting. Two systems of soil preparation (compaction and puddling) were studied for possible utilisation with a two-wheel rice transplanter in a very gravelly clay loam soil (Typic Haplocalcids, USDA; Haplic Calcisols, FAO). Compaction was done with a tractor equipped with a 5 Mg roller, whilst a rotary tiller and a locally made rigid-tine field cultivator, named Khishchee, were used for puddling. The transplanter worked well following both compaction and puddling rice soil preparation treatments. However, wheel slippage of the transplanter following compaction was less than after puddling. Transplanting was more uniform and seedling establishment was high after the compaction treatment as compared to puddling. In the soil compaction treatment, paddy yield was higher and plant lodging was lower than after puddling. Soil compaction reduced both water requirement and growth period of rice. These results suggest that soil compaction is a practical and perhaps a better method for mechanized rice transplanting than puddling in very gravelly soils.

Effect of pre-planting tillage on crop yields and weed biomass in a rice–wheat system on a sandy loam soil in Punjab

In rice ( Oryza sativa L.) culture the effect of puddling (wet tillage) on puddle quality, weed growth and yield of crop depends upon initial soil manipulations by pre-puddling tillage. However, the role of pre-puddling tillage on these aspects has not been studied adequately. These effects were studied for three years (1994–1996) in a field experiment with a rice–wheat ( Triticum aestivum L.) cropping system at Punjab Agricultural University, Ludhiana. Treatments included pre-puddling tillage treatments no tillage (PT 0), one discing one harrowing (PT 2) and one discing and three harrowings (PT 4)) in rice in combination with four tillage systems, varying in depth and intensity of soil disruption in wheat on puddle quality, weed growth and yield of rice and wheat on a sandy loam soil (Dystric Cambisol). Pre-puddling tillage improved puddle quality in terms of increased puddle depth and tended to decrease percolation rate. Weed infestation in rice decreased with increase in intensity of pre-puddling tillage. Mean dry weed biomass 35–40 days after transplanting was 1.6 Mg ha −1 in PT 0, 0.6 Mg ha −1 in PT 2 and 0.5 Mg ha −1 in PT 4. Leaving some area untilled between rows (strip tillage) in wheat resulted in a larger weed biomass in rice, than with inversion of soil. Pre-puddling tillage did not affect rice yield during the first two years but significantly increased it during the third year when rice yield was 4.1 Mg ha −1 in PT 0 compared with 5.8 Mg ha −1 in PT 2 and 6.1 Mg ha −1 in PT 4. Manual weeding at 40 days after transplanting masked the effect of pre-puddling tillage on rice yield. In general, rice yield decreased exponentially with increase in weed biomass recorded at harvest of the rice crop. Pre-puddling tillage did not affect wheat yield significantly. The results suggest that for effective weed control, high rice yield and water use efficiency, the field must receive pre-puddling tillage at least once.

Effect of puddling on soil desalinization and rice seedling survival in the Senegal River Delta

Soils in the Senegal River Delta are naturally sodic and saline due to the presence of fossil salt deposits in the subsoil. Such soils are being used for rice ( Oryza sativa L.), using pump irrigation. Before the onset of the growing season, farmers dry till and flush their rice field with fresh irrigation water to wash out salts from the root zone. We tested the potential of plowing under water-saturated conditions (puddling) to increase the amount of salt washed out from the topsoil with surface drainage. In a 1995 field experiment, salt removal using conventional dry soil-tillage and five irrigation-drainage cycles was compared with wet tillage (1, 2 or 3 times puddling) using a hydro-tiller and five irrigation-drainage cycles. Repetitive puddling and surface water drainage was very effective in removing salt from the soil profile. Each puddling, followed by surface drainage removed ca. 4.3 t salt ha −1, as opposed to ≈1 t salt ha −1 per flushing in the dry tilled plots. However, depth of the puddled layer increased after each puddling, and new salt from the subsoil was, therefore, brought in solution. Puddling had a negative effect on rice seedling establishment, presumably because it induced a lower but homogeneous salt distribution in the puddled layer. We concluded that introduction of the hydro-tiller in the Senegal River Delta as a replacement for conventional dry tillage cannot be recommended. The hydro-tiller may be used to accelerate reclamation of highly saline areas for rice cropping if a constant tillage depth can be maintained, and if the soil is allowed to regain structure after puddling. Before a reclaimed field is direct-seeded, test sowing and monitoring of survival rate for at least a week is recommended.

Water management in various crop production systems related to soil tillage

Soil tillage, of different types and intensity and performed at different antecedent soil moisture conditions, is an important tool for agricultural water management. Tillage systems have important applications for increasing irrigation efficiency, enhancing the effectiveness of drainage systems, improving water quality, decreasing runoff losses and minimizing soil erosion, increasing runoff losses for water harvesting and supplemental irrigation, and decreasing percolation losses and creating aquatic environments for rice cultivation. The versatility and diversity of applications of tillage systems depend on the choice of tillage techniques. No-tillage methods with residue mulches are useful to conserve soil water. Chisel tillage and subsoiling methods along with ridge-tillage techniques are useful in increasing irrigation efficiency. No-tillage systems are useful in decreasing sediment density and transport of sediment laden pollutants in runoff, and puddling and wet tillage techniques or soil compaction are used in rice cultivation. Finally soil compaction and techniques to increase water repellence are useful for water harvesting for subsequent use in supplemental irrigation.

Effect of puddling (wet tillage) on rice yield and physico-chemical properties of soil

The effect of puddling (wet tillage) after the onset of monsoon in an established rice crop treated with pre-emergence Saturn or hand weeded was evaluated for two consecutive kharif seasons during 1984 and 1985. Physical and chemical changes in the silty clay loam soil (0–15 cm) and rice grain yield were recorded after the harvest of the crop. Dry matter accumulation of weeds at the heading stage of the rice crop was also studied.

Land preparation requirements for rainfed rice as affected by climatic water balance and tillage properties of lowland soils

Tillage effects on four lowland soils were evaluated and the relationship between climatic water balance ( W = difference between cumulative rainfall and evaporation) and rice ( Oryza sativa L. var. IR20) response to land preparation was determined under rainfed conditions. Tillage treatments included zero tillage, rototilling, conventional plowing, shallow puddling and thorough puddling. The soils were Maahas clay (Andaqueptic Haplaquoll), San Miguel sandy loam (Aeric Tropaquept), Maligaya clay loam (Vertic Tropaquept) and Maligaya clay (Vertic Tropaquept) Conventional plowing increased hydraulic conductivity ( K s) in all four soils. Wet tillage had the contrary effect, which was more apparent in sandy loam and clay loam soils than in clay soils. Soil penetration resistance decreased with increase n tillage intensity under favorable climatic water balance ( W > 100 cm). Under inadequate moisture conditions ( W < 100 cm), however, conventional plowing was more favorable for soil tilth than was wet tillage. IR20 suffered a significant yield loss at K s > 1.31 cm day −1 when the root length density was <1.24 cm cm −3. Root activity was severely reduced at moisture stress > 0.005 MPa and soil penetration resistance > 0.57 MPa. Decreasing K s improved the profile moisture retention in sandy loam soil, but had no effect on moisture regime in clay soils with a shallow water table (0–30 cm deep) or in clay loam under high climatic water balance ( W > 100 cm). As a result, tillage had no effect on grain yield in clay soils with a shallow water table or in clay loam soil under high climatic water balance. In sandy loam, however, thorough puddling significantly increased grain production. It was concluded that tillage is not required to alleviate soil physical limitations in rainfed lowland rice production in low permeable soils under an adequate climatic water balance. Wet tillage is a prerequisite for rice productivity in medium- to coarse-textured soils in drought-prone environments, although thorough puddling showed no advantage over shallow puddling.

Degradation and restoration of soil structure in a cracking grey clay used for cotton production

A field experiment involving irrigated cotton investigated the effect of tillage on a self-mulching cracking grey clay at three different soil water contents: dry (close to permanent wilting point to over 1 m depth), moist (subsoil close to the lower plastic limit) and wet (just trafficable). These treatments had been repeated over three years prior to the plant and soil measurements reported in this paper. Compared with tillage of dry soil, tillage of moist or wet soil depressed lint yield by 35% (P&lt;0.001). Shrinkage curves of resin-coated, intact soil clods showed lower clod bulk density at a standard water content in the dry treatment than in the wet treatment (P&lt;0.001). This difference was most marked in the 0.2-0.3 m depth, where clods from the wet treatment had a bulk density approaching that of clods made from hand-remoulded soil. Subsequent restoration treatments showed that, although wheat improved soil physical condition, the yield of a following cotton crop was reduced due to lower nitrogen uptake (P&lt;0.001). Deep tillage alone increased clod bulk density but deep tillage after wheat decreased density (interaction P&lt;0.001 for the 0.2-0.3 m depth, P&lt;0.05 for the 0.3-0.4 m depth). These effects of deep tillage were not reflected in yield of cotton. Effects of the previous dry, moist and wet tillage treatments persisted but there was some improvement, even in the absence of restoration treatments. To preserve the structure and productivity of cracking clay soils, they should be tilled only when dry to permanent wilting point through the full depth of tillage.

A water balance model for rain-grown, lowland rice in northern Australia

A simple water balance model was developed for rain-grown, lowland rice on the heavy clay soils of the sub-coastal plain of the Adelaide River in northern Australia. The rice farming system is based on short duration (100 days) photoperiod-insensitive varieties. The seed bed is prepared in the flooded state with a tractor-driven rotary tiller. Aircraft are used to broadcast seed, fertilizer, and pesticides into the flooded fields. The crop is sown during mid-January to early February when rainfall and tillage criteria are satisfied. The model is based mainly on field measurements of evapotranspiration. Estimated dates of soil saturation and depths of ponded water at Coastal Plains Research Station agreed remarkably well with observed values in five wet seasons having widely different rainfall patterns. The model was used to estimate the success frequency of rain-grown, lowland rice at Darwin, Koolpinyah, and Humpty Doo with 93, 48, and 24 years of rainfall records respectively. A computer program was written to obtain daily estimates of soil water storage and depth of ponded water for each wet season from September 1 to May 31. In the program provision was made for maximum field pondage to be successively 6, 8, 10, and 12 inches. Rainfall was regarded as adequate providing there were (a) at least 14 days pondage ≥3 inches between December 31 and February 18 for wet tillage before sowing, (b) at least 80 days between sowing date and the last date at which ponded water was present on the field, (c) not more than 10 consecutive zero pondage days between 50 and 80 days after sowing, corresponding to the stage of panicle initiation through flowering. A 23-year comparison showed that on the average, the water availability was similar at the three stations, although differences sometimes occurred within individual seasons. The results indicate that the expectation of crop failure due to inadequate rainfall at Darwin is about 1 year in 30. In addition there is an expectation of major yield reduction of about 1 year in 10. The seasons of crop failure and low yield tended to occur in groups after relatively long runs of seasons of adequate rainfall. Designing for a maximum field pondage greater than 10 inches did not reduce the estimated number of crop failures at any station. The results are discussed in relation to practical farming operations.