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1.
Puddling as well as no-puddling for growing transplanted and direct seeded rice, respectively, have their disadvantages as well as advantages on the physical condition of the soil and yield of rice. The soil that is more susceptible to changes in structure is easy to puddle. However, what should be the extent of puddling is not well established. Generally, farmers have a tendency to create a very fine puddle that actually may not be required. Keeping in view the current global emphasis on conservation of resources as well as reduction of the production cost to improve the economic gain of farmers, this study attempted to find out the influence of varying intensities of puddling on the soil physical condition and rice yield (cv. IR 36) in a Vertisol of central India. The study was conducted over two cropping seasons during year 2000 and 2001. Three puddling intensities i.e. no-puddling ( P0), and puddling by four ( P1) and eight ( P2) passes of a 5 hp power tiller were evaluated. The aggregate mean weight diameter (AMWD) of soil (0–15 cm depth) for P0 remained almost unchanged till harvest. At 15 days after puddling, AMWD in P1 and P2 compared to P0 was less by 45 and 59% in the first year and by 60 and 69% in the second year, respectively. These values at harvest changed to 22 and 46% in the year 2000 and 28 and 43% in the year 2001, respectively. Soil bulk density (BD) and penetration resistance (PR) increased significantly from transplanting to harvest in puddled soil, but in unpuddled soil significant increase in PR only at the surface 0–7 cm layer was observed. Higher intensity of puddling favoured more soil wetness at harvest, as the puddled soil maintained 25% more water than P0. Compared to P1, P2 showed an increase of 4.3, 10.3 and 7.7% in length, width and depth of cracks, respectively, while the increase in P1 over P0 in the same order was 35, 23.5 and 13.3%, respectively. Thus, crack dimensions (length, width and depth) were larger under high intensity of puddling. Water loss through seepage plus percolation was significantly higher in P0 as compared to P1 and P2 and the higher intensity of puddling reduced the losses more. The grain yield of P2 was slightly higher than P1 but both were significantly above P0. Higher grain yield resulted in 46 and 49% more water use efficiency under P1 and P2 than P0, respectively. This 2-year study has shown that puddling beyond P1 i.e., four passes of a 5 hp power tiller may not be required to obtain higher yield or other benefits in Vertisols having similar hydrology to that reported here. Puddling only to the required level will also deteriorate less the soil physical condition as compared to more intense puddling. The unpuddled direct seeded rice maintained the soil in a better physical condition but the yield was significantly lower in relation to the puddled ones. 相似文献
2.
Rice–wheat productivity in irrigated tract of the Indo-Gangetic plains is constrained by water and energy limitations. In order to minimize unproductive soil water evaporation and percolation loss at a field scale, management practices include soil puddling, water-economizing irrigation schedule, and matching growth cycle with periods of low evaporative demand. This 3-year field study examines combined effects of these options on rice–wheat productivity and water-use efficiency (WUE) and energy-use efficiency (EUE) on a sandy loam soil in an irrigated semi-arid sub-tropical environment. Treatments included combinations of three puddling intensities, viz., one ( P1), two ( P2), and four ( P4) runs of a tine cultivator in ponded water after a common pre-puddling tillage; with two irrigation regimes, viz., continuous submergence ( I1) throughout the growing season, and intermittent submergence ( I2) with continuous submergence for 2 weeks after transplanting followed by 2-day interval between successive irrigations, and two transplanting dates, viz., first fortnight of June ( D1) and end June ( D2) to impose variation in seasonal evaporative demand. Residual effect of puddling in rice on succeeding wheat was also evaluated during the 3 years. Intensive puddling and water-economizing schedule caused a significant reduction in seasonal percolation loss primarily due to puddling-induced changes in soil bulk density and hydraulic behavior. Increasing puddling intensity from P1 to P2 enhanced mean rice yield by 0.2–0.3 Mg ha−1, but additional puddling did not improve yield significantly. Mean grain yield increase with I1 over I2 ranged between 0.3 and 0.6 Mg ha−1. Interaction effect between puddling and irrigation indicate that yield benefit with I1 over I2 was greatest in P1 regime (0.6 Mg ha−1), and the effect decreased with increase in puddling intensity. Delayed transplanting caused a decline of 0.3–0.5 Mg ha−1 in rice yield. Although maximum yield was realized with combination of P2 or P4 regime with I1 regime, but water-use efficiency was greater with I2 compared to I1 regime by 1.1 kg ha−1 mm−1 in 2000 and by 0.3 kg ha−1 mm−1 in 2001. It indicates that yield gain with additional irrigation were not commensurate with additional water input. Energy analysis also showed that energy-use efficiency was 6.8, 7.2, and 6.6 kg kWh−1 for P1, P2, and P4 regimes suggesting that yield gain with P4 did not match energy input for additional puddling. Further, there was a greater risk of yield reduction of succeeding wheat with P4 (by 0.2–0.3 Mg ha−1) compared to P1 or P2 regime. 相似文献
3.
Many farmers in southeast Asia are growing rice on unpuddled soil. This practice does not permit breaking of the deadlock of increase in productivity in spite of using high yielding varieties and practising all known scientific technologies. Furthermore, farmers do dry seeding which leads to heavy infestation of weeds and reduces response to other inputs. Similarly, in rice–wheat belt due to short turn around time farmers resort to broadcast sowing of wheat after rice and no data on benefits or otherwise of tillage are available. A field study was therefore conducted for 3 years (1993–1994 to 1995–1996) at the Indian Agricultural Research Institute, New Delhi to study the effect of tillage and seeding methods in rice–wheat cropping system. Treatments included four combinations of two puddling treatments (puddling and no puddling) and two methods of rice seeding (direct seeding and transplanting) in rice and two tillage treatments (zero and conventional tillage) in wheat. Results indicated that puddling increased grain yield of rice by 0.7–1 t ha −1 and of succeeding wheat by 0.2–0.4 t ha −1, straw yield of rice by 0.8–1.7 t ha −1 and of succeeding wheat by 0.1–1.0 t ha −1. Puddling reduced water requirement of rice by 75 mm ha and increased net return of rice–wheat system by US $175 ha−1. Transplanted rice gave significantly higher grain and straw yields and net returns than direct seeded rice both on puddled and unpuddled seedbed. Conventional tillage in wheat also increased productivity of rice–wheat cropping system significantly over zero tillage after both puddled and non-puddled rice. Our results thus show that rice should be grown on puddled soil and wheat after rice should be sown after conventional tillage. 相似文献
4.
One of the resource conservation technologies for rice ( Oryza sativa) is direct seeding technique, which may be more water efficient and labour cost-effective apart from being conducive for mechanization. The crop establishment during the initial stages may depend upon the method of direct seeding, cultivar and seed rate. A study was carried out during 2004–2005 to evaluate the effect of different seeding techniques, cultivars and seed rates on the performance of direct-seeded basmati rice in loamy sand (coarse loamy, calcareous, mixed hyperthermic, Typic Ustipsamments) at Punjab Agricultural University, Ludhiana, India. The treatments in main plots included four seeding techniques (broadcast in puddled plots, direct drilling in puddled plots, direct drilling in compacted plots and direct drilling under unpuddled and uncompacted conditions). The subplots treatments comprised of two cultivars (Pusa Basmati-1 and Basmati-386) and three seed rates (at 30, 40 and 50 kg ha −1). The moisture retention and bulk density at harvest were sufficiently lower in uncompacted/unpuddled plots than compacted or puddled plots more so in 0–30 cm soil layer. The crop stand establishment was higher in direct-drilled compacted plots with 50 kg seed ha−1. It was higher in Pusa Basmati-1 than Basmati-386. The direct drilling after compaction produced 28% higher biomass than uncompacted/unpuddled plots. Similar trend was observed in leaf area index and effective tillers. Effective tillers were significantly higher with 30 kg seed ha−1and were higher in Pusa Basmati-1 than Basmati-386. The root mass density of basmati rice in 0–15 cm soil layer at 45 days after sowing was 1549 g m−3 in compacted soils, 1258 g m−3 in broadcasting in puddled soil and 994 g m−3 with direct drilling in puddled soil. The grain yield of basmati rice was 44% and 30% higher in direct-drilled compacted and puddled plots, respectively, than uncompacted/unpuddled plots. 相似文献
5.
The prolonged use of vehicular traffic for farming creates subsoil compaction, which reduces crop yield and deteriorates the physical conditions of the soil. Field experiments were conducted during 2002–2003 and 2003–2004 in Pakistan to study subsoil compaction effects on soil bulk density, total porosity, yield and yield components of wheat. Soil compaction was artificially created at the start of the experiment using 7.0 t roller having length of 1.5 m and diameter of 1.22 m. Treatments consisted of T 1 = control (no compaction), T 2 = two passes of roller, T 3 = four passes of roller, T 4 = six passes of roller. The experiments were arranged in randomised complete block with four replications. Results indicated that subsoil compaction adversely affected the bulk density, total porosity of soil and root length during both the years. Soil compaction increased the bulk density (BD) from 1.37 for T 1 to 1.57, 1.61 and 1.72 Mg m −3 whereas decreased the total porosity from 47.3% for T 1 to 40.0, 37.4 and 34.5% for T 2, T 3 and T 4, respectively. Similarly grain yield decreased from 4141.7 for T 1 to 3912.8, 3364.5 and 3010.3 kg ha −1 for T 2, T 3 and T 4, respectively. The deteriorating effect of compaction depended upon the degree of compaction. Subsoil compaction adversely affected the yield and yield attributes of wheat during both years of experiments. The subsoil compaction adversely affected soil physical conditions, which substantially decreased the yield of wheat. Therefore, appropriate measures of periodic chiselling, controlled traffic, conservation tillage, and incorporating of crops with deep tap root system in rotation cycle is necessary to minimize the risks of subsoil compaction. 相似文献
6.
Coarse-textured soils are puddled to reduce high percolation losses of irrigation water under rice ( Oryza sativa L.). This practice, however, reduces yield of succeeding wheat ( Triticum aestivum L.) owing to deterioration in soil physical conditions. The 6 year field study reported in this paper evaluated the effects of puddling level and integrated N management on the development of subsurface compaction and growth and yield of rice and the following spring wheat grown in 1 year sequence on a sandy loam soil. Treatments were combinations of three puddling levels: low (one discing and one planking), medium (two discings and one planking), and high (four discings and one planking), and three nitrogen sources: (1) 120 kg N ha −1 from urea, (2) 60 kg N ha −1 from urea plus sesbania ( Sesbania aculeata Pers.) green manure, and (3) 60 kg N ha −1 from urea plus 20 Mg ha −1 farmyard manure. Percolation rate decreased from 14 mm day −1 with low puddling to 10 mm day −1 with high puddling, with a corresponding reduction in irrigation water requirement of rice of about 20%. Bulk density profiles in the 0–30 cm soil layer showed the formation of a compact layer at 15–20 cm depth, and bulk density increased with puddling level and cropping season. The impact of organic amendments in reducing bulk density was immediate, but the rate of increase in bulk density with time was the same in all the nitrogen sources. Organic amendments did not affect percolation rate and irrigation requirement of rice. Rice yields were not significantly affected by puddling and N source treatments throughout the study period. Residual effects of treatments on wheat yield were observed from the second season onwards. Interactive effects of puddling and N source on yields of rice and succeeding wheat were not significant. Yield differences in wheat between high and low puddling were 8% and 11% during the second and the fifth cropping season, respectively. This study indicates that medium puddling was optimum, as it reduced percolation without decreasing yield of succeeding wheat. 相似文献
7.
Soil puddling in advance of rice ( Oryza sativa L.) transplanting disperses surface aggregates and generates compaction at depth. As a management scheme for rice, puddling is typically considered advantageous for maximizing resource availability and yield. However, some experimental findings suggest a conflict between edaphic conditions created by this establishment technique and the performance of subsequent non-rice crops like wheat ( Triticum aestivum L.). At a site in the mid-hills region of Nepal on a silt loam soil with vertic characteristics, we compared the impact of six rice tillage (surface tillage—T 1, shank subsoiler—T 2, shank subsoiler + moldboard plough—T 3) and establishment (soil puddling + transplanting—TPR, direct seeding—DSR) combinations on soil physical properties over two cycles of the rice–wheat rotation. For the rice season, 0–20 cm saturated hydraulic conductivity ( Ksat) in the DSR plots was 2.6 and 4.3 times higher than their TPR counterparts in the first (Y 1) and second (Y 2) years, respectively (TPR-Y 1 = 93 mm day −1, DSR-Y 1 = 241 mm day −1, TPR-Y 2 = 133 mm day −1, DSR-Y 2 = 582 mm day −1), whereas tillage method did not significantly influence Ksat in this soil layer. The impact of rice establishment method was reflected in higher TPR bulk densities in the 5–10 (DSR = 1.19 g cm −3, TPR = 1.24 g cm −3) and 10–15 cm (DSR = 1.24 g cm −3, TPR = 1.29 g cm −3) depth increments in the wet season. Although none of the treatments significantly influenced the position or thickness of the plough sole, penetration resistance profiles suggest that vertical fractures with reduced soil strength were created within the pan region by deep tillage (T 2 and T 3), although these features were not associated with higher hydraulic conductivities from 20 to 50 cm. As the soils dried at the end of the rice season, crack propagation in the deep tilled plots (T 2 and T 3) was more pervasive. During the wheat season, comparable bulk density profiles and soil moisture retention characteristics across the treatments suggest that many of the edaphic changes induced by contrasting rice tillage and establishment practices did not persist in the self-mulching, vertic soils at our site. Conversely, significant increases in Ksat among the DSR plots from Y 1 to Y 2 (Y 1 = 241 mm day −1, Y 2 = 582 mm day −1) imply a temporal element to soil structural regeneration with adoption of direct seeding. 相似文献
8.
Two similar experiments were conducted over a 3 year period on a clay soil to compare the effects of different intensities of traffic, ranging from 0 to 124 t km ha −1 (1.24 MN km ha −1) on the energy required for ploughing and secondary cultivation. The tilths produced by these operations were measured by sieving and, in one year, by image analysis of sections cut from large blocks of resin-impregnated soil. Both energy required for cultivation and mean aggregate size after ploughing were related to the intensity of wheeling and the soil water content at ploughing. In the absence of wheeling, energy for ploughing was reduced by between 17 and 45%, and mean aggregate size was reduced to 20–70% of that resulting from a conventional tractor and plough-based system. Specific draught in the driest soil conditions was almost twice that in the wettest conditions. The geometric mean diameter of aggregates produced by the mouldboard plough ranged from 7 mm in a wetter year and with no traffic to 140 mm in the driest year with a year-round tractor traffic system. Scanning sections of large impregnated blocks with an image analyser provided more detailed information on aggregate size distributions within the plough layer than did sieving, and it also provided information on pore size distributions. This technique served to illustrate large differences in soil macrostructure between a conventional tractor and plough cultivation system compared with an untrafficked but ploughed soil. 相似文献
9.
Application of urban refuse compost to agricultural soil could help to solve municipalities' problems related to the increasing production of waste only if soil property improvement and environmental conservation can be demonstrated. The use of low-pressure tractor tyres is another proposal in modern agriculture for reducing soil compaction. This study thus aimed to detect the effects of both compost and low-pressure tractor tyres on soil loss, runoff, aggregate stability, bulk density, penetrometer resistance and maize ( Zea mays L.) yield. A 3-year field experiment was carried out on a hilly (15% slope) clay loam soil in central Italy. Twelve plots (200 m 2 each) were monitored with tipping-pot devices for runoff and soil erosion measurement. Treatments were: compost addition (64 Mg ha −1), mineral fertilisation, use of low-pressure tyres, use of traditional tyres, with three replicates, in a fully randomised block design. Compost was applied once at the beginning of the experiment. Runoff reduction due to compost ranged between 7 and 399 m 3 ha −1 during seasons, while soil erosion was reduced between 0.2 and 2.4 Mg ha −1. Mean weight diameter (MWD) of stable aggregates, measured on wheel tracks, increased by 2.19 mm, then progressively decreased. Compost significantly increased bulk density by 0.08 Mg m −3 due to its inert fraction content. This effect was less evident in the second and third year, probably due to harrowing. Maize yields were slightly, but significantly, reduced in composted plots by 1.72 Mg ha −1 in the third year. Low-pressure tyres significantly reduced soil loss in the third year by 1 Mg ha −1. Furthermore, they did not significantly influence runoff volumes and soil structural stability. Low-pressure tyres or compost addition were singly able to prevent an increase in penetrometer resistance due to agricultural machinery traffic. Low-pressure tyres increased the maize yield during the 3 years and the difference (0.4 Mg ha −1) became significant in the third year. In conclusion, results show the positive lasting effect of compost in ameliorating soil physical properties and reducing runoff and soil erosion. Low-pressure tyres appear justifiable both for the observed increase of grain production and reduction of soil compaction. This latter effect is, nevertheless, masked by compost addition which is also able to reduce penetrometer resistance. Further research is required to explain the causes of the slight inhibition of grain yield observed when compost was compared with mineral fertilisation. 相似文献
10.
An experiment was conducted to evaluate the effects of tillage and residue incorporation on soil properties and yields of rice ( Oryza sativa L.) and wheat ( Triticum aestivum L.) in rotation for 4 years on a silty clay loam of an Aquic Hapludoll with natural water table fluctuating between 0.05 and 0.97 m depth The rice experiment was laid out in split plot design with four levels of tillage, viz. conventional puddling (CP), puddling by four passes of rotavator (PR), reduced puddling by two passes of rotavator (ReP), and direct seeding without puddling (DSWP) and two levels of residue, viz. residue incorporation (RI) and residue removal (RR) in four replications. The treatments for wheat were zero tillage (ZT) and conventional tillage (CT) with RI and RR superimposed over the plots of rice. Tillage for rice increased puddling index and bulk density (BD) over the years. The increase was significantly higher in CP and PR than in ReP. In wheat season, BD was higher under ZT than under CT but the differences were not significant. Puddling decreased saturated hydraulic conductivity with time, which became significantly lower in CP and PR in the fourth year than in ReP in the first year. Infiltration rate (IR) also decreased with time and was lowest in CP and PR. In wheat season, IR was at par under ZT and CT. Rice yield in PR was maximum and at par with that in ReP. But wheat yield was lowest in PR and highest in DSWP, and was at par in DSWP and ReP. Thus, rice yields were optimum under ReP, in which changes in soil properties were least, and wheat yields were optimum both under ZT and CT in the DSWP and ReP plots of rice under shallow water table conditions of the silty clay loam. 相似文献
11.
In the Ethiopian highlands, large-scale stone bund building programs are implemented to curb severe soil erosion. Development of soil fertility gradients is often mentioned as the major drawback of stone bund implementation, as it would result in a dramatic lowering of crop yield. Therefore, the objectives of this study are to assess soil fertility gradients on progressive terraces and their influence on crop yield, in order to evaluate the long-term sustainability of stone bunds in the Ethiopian Highlands. The study was performed near Hagere Selam, Tigray and comprises (i) measurement of Pav, Ntot and Corg along the slope on 20 representative plots and (ii) crop response measurement on 143 plots. Results indicate that levels of Pav, Ntot and Corg in the plough layer are highly variable between plots and mainly determined by small-scale soil and environmental features, plot history and management. After correcting for this “plot effect” a significant relationship (p < 0.01) was found between the position in the plot relative to the stone bund and levels of Pav and Ntot, which are higher near the lower stone bund, especially on limestone parent material. For Corg and on basalt-derived soils in general no significant relationship was found. Although soil fertility gradients are present, they are not problematic and can be compensated by adapted soil management. Only in areas where a Calcaric or Calcic horizon is present at shallow depth, care should be taken. Crop Yields increased by 7% compared to the situation without stone bunds, if a land occupation of 8% by the structures is accounted for. Yield increased from 632 to 683 kg ha−1 for cereals, from 501 to 556 kg ha−1 (11%) for Eragrostis tef and from 335 to 351 kg ha−1 for Cicer arietinum. No negative effects reducing stone-bund sustainability were found in this study. Soil erosion on the other hand, poses a major threat to agricultural productivity. Stone bund implementation therefore is of vital importance in fighting desertification and establishing sustainable agriculture in the Ethiopian highlands. 相似文献
12.
The effect of soil incorporations of lantana ( Lantana spp.) biomass, an obnoxious weed, on physical environment of a silty clay loam soil (Typic Hapludalf) under rice ( Oryza sativa L.)–wheat ( Triticum aestivum L.) cropping was studied in a long-term field experiment conducted in a wet temperate region of north India. Fresh lantana biomass was incorporated into the plough layer at 10, 20 and 30 Mg ha −1 annually, 7–10 days before puddling. Plant-available water capacity (PAWC), non-limiting water range (NLWR) and NLWR:PAWC ratio were determined to characterize soil physical environment during wheat crop in the tenth cropping cycle. Ten annual applications of lantana at 10, 20 and 30 Mg ha−1, increased organic carbon (OC) content over control by 12.6, 17.6 and 27.9% in 0–15 cm soil layer, and 17.1, 26.3 and 39.5% in 15–30 cm soil layer, respectively. The OC content in 0–15 and 15–30 cm soil layer of control plots was 11.1 and 7.6 g kg−1 soil. Bulk density decreased by 3–14% in 7.5–10.5 cm layer and 1–6% in 15–18 cm layer. Volumetric moisture contents at 10% air-filled porosity were 38.4, 40.0, 54.5 and 55.7% at 7.5–10.5 cm depth, and 31.4, 32.2, 33.9 and 34.6% at 15–18 cm depth corresponding to 0, 10, 20 and 30 Mg ha−1 lantana treatment, respectively. At 15–18 cm soil depth, volumetric moisture contents at 2 MPa soil penetration resistance were 26.9, 24.8, 23.0 and 19.6% in zero, 10, 20 and 30 Mg ha−1 lantana-treated plots, respectively. Lower soil water contents associated with 10% air-filled porosity and greater soil water contents associated with a limiting penetration resistance of 2 MPa resulted in a lower NLWR (4.3%) for control as compared to lantana-treated soil (7.4–15.1%). The PAWC showed slight increase from 12.9 to 13.4–14.9% due to lantana additions. The NLWR:PAWC ratio was also lower in control (0.33) as compared to lantana-treated soil (0.55–1.01). The NLWR was significantly and positively correlated with wheat grain yield (r=0.858**). 相似文献
13.
Soil fertility, one of the important determinants of agricultural productivity, is generally thought to be supplemented through the application of nutrients mainly through inorganic fertilizers. The physical fertility of the soil, which creates suitable environment for the availability and uptake of these nutrients, is generally ignored. The present study aims to characterize the soil physical environment in relation to the long term application of farm yard manure (FYM) and inorganic fertilizers in rice–wheat. The treatments during both rice and wheat crops were (i) farm yard manure @ 20 t ha −1 (FYM); (ii) nitrogen @ 120 kg ha −1 (N 120); (iii) nitrogen and phosphorus @ 120 and 30 kg ha −1 (N 120P 30) and (iv) nitrogen, phosphorus and potassium @ 120, 30 and 30 kg ha −1 (N 120P 30K 30) in addition to (iv) control treatment, i.e. without any fertilizer and/or FYM addition. The treatments were replicated four times in randomized block design in a sandy loam (typic Ustipsament, non-saline, slightly alkaline). Bulk density, structural stability of soil aggregates and water holding capacity of 0–60 cm soil layer were measured. The average mean weight diameter (MWD) was highest in FYM-plots both in rice (0.237 mm) and wheat (0.249 mm) closely followed by that in N120P30K30 plots. The effect of FYM in increasing the MWD decreased with soil depth. The addition of both FYM and N120P30K30 increased the organic carbon by 44 and 37%, respectively in rice. The total porosity of soil increased with the application of both FYM and N120P30K30 from that in control plots. In 0–15 cm soil layer, the total porosity increased by 25% with FYM from that in control plots. This difference decreased to 13% in 15–30 cm soil layer. The average water holding capacity (WHC) was 16 and 11% higher with FYM and N120P30K30 application from that in control plots. The MWD, total porosity and WHC improved with the application of balanced application of fertilizers. The grain yield and uptake of N, P and K by both rice and wheat were higher with the application of FYM and inorganic fertilizers than in control plots. The carbon sequestration rate after 32 years was maximum (0.31 t ha−1 year−1) in FYM-plots, followed by 0.26 t ha−1 year−1 in N120P30K30-plots, 0.19 t ha−1 year−1 in N120P30 and minimum (0.13 t ha−1 year−1) in N120-plots. 相似文献
14.
Depending upon how soil is managed, it can serve as a source or sink for atmospheric carbon dioxide (CO 2). As the atmospheric CO 2 concentration continues to increase, more attention is being focused on the soil as a possible sink for atmospheric CO 2. This study was conducted to examine the short-term effects of crop rotation and N fertilization on soil CO 2 emissions in Central Iowa. Soil CO 2 emissions were measured during the growing seasons of 2003 and 2004 from plots fertilized with three N rates (0, 135, and 270 kg N ha −1) in continuous corn and a corn–soybean rotation in a split-plot design. Soil samples were collected in the spring of 2004 from the 0–15 cm soil depth to determine soil organic C content. Crop residue input was estimated using a harvest index based on the measured crop yield. The results show that increasing N fertilization generally decreased soil CO 2 emissions and the continuous corn cropping system had higher soil CO 2 emissions than the corn–soybean rotation. Soil CO 2 emission rate at the peak time during the growing season and cumulative CO 2 under continuous corn increased by 24 and 18%, respectively compared to that from corn–soybean rotation. During this period, the soil fertilized with 270 kg N ha −1 emitted, on average, 23% less CO 2 than the soil fertilized with the other two N rates. The greatest difference in CO 2 emission rate was observed in 2004; where plots that received 0 N rate had 31% greater CO 2 emission rate than plots fertilized with 270 kg N ha −1. The findings of this research indicate that changes in cropping systems can have immediate impact on both rate and cumulative soil CO 2 emissions, where continuous corn caused greater soil CO 2 emissions than corn soybean rotation. 相似文献
15.
Reduced tillage techniques and direct seeding method that can replace the conventional methods, were examined in the western part of Turkey (Trakya Region) during the years of 1999 and 2000. In the experiment five tillage methods and no-tillage (DRD) were used. All tillage methods and direct seeding were applied in the dry soil conditions except conventional method. The tillage methods are heavy-duty disc harrow (DIS), plough (PLO), rotary tiller (ROT), tillage combination of tine, rotor and roller (TIC) and conventional tillage method in which plough is used in wet soil condition. The effects of the treatments on soil penetration resistance, mean emergence dates, percentage of emerged seedlings, plant height, stem diameter and silage corn yield were measured. All the parameters tested were found to be statistically significant. Direct seeding method gave the best result for mean of emergence dates (4.93 days) and percentage of emerged seedlings (95.48%). The best result for silage yield (69.32 Mg ha−1) was found in tillage combination. The lowest yield (58.92 Mg ha−1) was found in the heavy-duty disc harrow tillage method. Direct seeding gives the best results for tillage efficiency parameters, such as fuel consumption, effective power requirement and field efficiency. Reduced tillage and direct seeding methods can be used in second crop silage corn in the region. 相似文献
16.
Field experiments were conducted on a clay soil in entisol to determine the effect of different tillage tools on soil properties, emergence rate index and yield of wheat in Middle Anatolia. There were four different tillage treatments: mouldboard ploughing followed by disc harrowing twice; rotary tillage twice; stubble cultivator followed by a disc harrowing; heavy globe disc twice. The smallest aggregate mean weight diameters and surface roughness were produced by rotary tillage. Decreasing mean weight diameter decreased the surface roughness. There was a significant ( P < 0.01) effect of the four different tillage systems on moisture content, bulk density, penetration resistance, aggregate mean weight diameter and surface roughness. Tillage systems had a significant effect on emergence rate and yield of wheat. Emergence rate index and yield of wheat varied from 15.24 to 18.88 and from 3065 kg ha −1 to 4265 kg ha −1, respectively. The greatest emergence rate index and yield were obtained with stubble cultivator followed by disc harrowing treatment. 相似文献
18.
A long-term field experiment with continuous corn, corn–soybean, and corn–alfalfa rotations, and different organic and inorganic soil nitrogen amendments was established at Ottawa, Ont., in 1991. Amendments applied to continuous corn were none, inorganic fertilizer at 100 and 200 kg N ha −1, stockpiled and rotted manure, each at 50 and 100 Mg ha −1 (wet weight). Amendments applied in the corn year to the 2-year rotations were none, inorganic fertilizer at 100 kg N ha −1, and stockpiled and rotted manure at 50 Mg ha −1. Mouldboard plow draft and tractor fuel consumption measurements were made with Agriculture and Agri-Food Canada’s instrumented research tractor in conjunction with normal fall tillage in 1991 prior to amendment application, and for 4 years from 1996 to 1999. Results showed a small difference among the amendment treatments in 1996 and 1997, and a much larger difference in 1998 and 1999. After 8 years of amendment application, plots receiving the manure amendments at the high rates exhibited from 27 to 38% lower plow draft and 13 to 18% lower tractor fuel consumption than those receiving the inorganic fertilizer. The difference was less for plots receiving the lower manure rates. The same trend occurred in the 2-year rotation plots where manures were applied in alternate years, although, the differences were much lower, and not always significant. The data clearly show that changes in soil structure and organic matter accompanying repeated applications of manure are manifested in reduced tillage energy. 相似文献
19.
Manure is a source of plant nutrients and can make a valuable contribution to soil organic matter (SOM). Two experimental sites were studied on a Halpic Phaeozem soil near Bad Lauchstadt in Germany. The first experiment, called the static experiment, commenced in 1902. The impact of fresh farmyard manure (FYM) (0, 20 and 30 t ha −1 2 year −1) combined with P, K and N fertiliser application on total organic C (C T), labile C (C L), non-labile C (C NL), total N (N T), mean weight diameter (MWD) and unsaturated hydraulic conductivity ( Kunsat) was investigated. The second experiment commenced in 1984 and investigated the effect of extreme rates of fresh FYM applications (0, 50, 100 and 200 t ha −1 year −1) and cropping, or a continuous tilled fallow on the same soil properties. At both sites a nearby grassland site served as a reference. On the static experiment, FYM application increased all C fractions, particularly C L, where application of 30 t ha −1 2 year −1 increased C L by 70% compared with no FYM application. Fertiliser additions to the static experiment had a positive influence on C fractions while N T increased from both FYM and fertiliser application. MWD increased as a result of FYM application, but did not reach that of the grassland site. Both fertiliser and FYM application increased Kunsat (10 mm tension) on the static experiment. In the second experiment application of 200 t ha −1 year −1 of FYM increased concentrations of C L by 173% and of C NL by 80%, compared with no FYM application to make them equivalent to, or greater than the grassland site. A continuously tilled fallow resulted in significant decreases in all C fractions, N T and MWD compared with the cropped site, while Kunsat (10 mm tension) was increased on the 0 and 50 t ha −1 year −1 treatments as a result of a recent tillage. There was no difference in Kunsat between the cropped and the continuous tilled fallow at FYM applications of 100 and 200 t ha −1 year −1. There were similar significant positive correlations of all C fractions and N T with MWD on both experimental sites but the relationships were much stronger on the extreme FYM experiment. Weaker relationships of C fractions and N T with Kunsat (10 mm tension) occurred for the static experimental site but these were not significant for the extreme FYM experimental site. The strongest relationship between C fractions and Kunsat was with C L. This research has shown that applications of FYM can increase SOM and improve soil physical fertility. However, the potential risk of very high rates of FYM on the environment need to be taken into consideration, especially since the application of organic materials to soils is likely to increase in the future. 相似文献
20.
There has been a trend toward increased cropping intensity and decreased tillage intensity in the semiarid region of the Canadian prairies. The impact of these changes on sequestration of atmospheric CO 2 in soil organic carbon (C) is uncertain. Our objective was to quantify the changes in total, mineralizable and light fraction organic C and nitrogen (N) due to the adoption of continuous cropping and conservation tillage practices. We sampled three individual long-term experiments at Lethbridge, Alberta, in September 1992: a spring wheat ( Triticum aestivum L.)-fallow tillage study, a continuous spring wheat tillage study and a winter wheat rotation-tillage study. Treatments had been in place for 3–16 years. In the spring wheat-fallow study, different intensities (one-way disc > heavy-duty cultivator > blade cultivator) of conventional tillage (CT) were compared with minimum tillage (MT) and zero tillage (ZT). After 16 years, total organic C was 2.2 Mg ha −1 lower in more intensively worked CT treatments (one-way disc, heavy-duty cultivator) than in the least-intensive CT treatment (blade cultivator). The CT with the blade cultivator and ZT treatments had similar levels of organic C. The CT treatments with the one-way disc and heavy-duty cultivator had light fraction C and N and mineralizable N amounts that were about 13–18% lower than the CT with the blade cultivator, MT or ZT treatments. In the continuous spring wheat study, 8 years of ZT increased total organic C by 2 Mg ha −1, and increased mineralizable and light fraction C and N by 15–27%, compared with CT with a heavy-duty cultivator prior to planting. In the winter wheat rotation-tillage study, total organic C was 2 Mg ha −1 higher in a continuous winter wheat (WW) rotation compared with that in a winter wheat-fallow rotation. The lack of an organic C response to ZT on the WW rotation may have been due to moldboard plowing of the ZT treatment in 1989 (6 years after establishment and 3 years before soil sampling), in an effort to control a severe infestation of downy brome ( Bromus tectorum L.). Our results suggest that although relative increases in soil organic matter were small, increases due to adoption of ZT were greater and occurred much faster in continuously cropped than in fallow-based rotations. Hence intensification of cropping practices, by elimination of fallow and moving toward continuous cropping, is the first step toward increased C sequestration. Reducing tillage intensity, by the adoption of ZT, enhances the cropping intensity effect. 相似文献
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