Effects of sowing date, tillage and residue management on productivity of cotton (Gossypium hirsutum L.)–wheat (Triticum aestivum L.) system in northwest India

In southwestern region of Punjab in north India, sowing dates of cotton crop in cotton (Gossypium hirsutum L.)–wheat (Triticum aestivum L.) system are staggered from last week of April to mid of May depending upon the surface water supply from canal as ground water is not fit for irrigation. Further, farmers practice intensive cultivation for seedbed preparation and burning of wheat straw before sowing of cotton crop. With the present farmers’ practices, yields have become static and system has become non-profitable. Field experiments were conducted on Entisols for two rotations of cotton–wheat system during the years of 2004–2005 and 2005–2006 in split plot design to study the direct and interactive effects of date of sowing and tillage-plus-wheat residue management practices on growth and yield of cotton and wheat and to increase the profitability by reducing the tillage operations, which costs about 50% of the sowing cost. The pooled analysis showed that in cotton crop, there was a significant interaction between year × dates of sowing. Among different tillage-plus-wheat residue management practices yields were 23–39% higher in tillage treatments than minimum-tillage. In wheat, grain yield in tillage treatments were at par. Water productivity amongst the tillage treatments in cotton was 19–27% less in minimum tillage than others tillage treatments. Similar trend was found in wheat crop. Remunerability of the cotton–wheat system was more with a combination of reduced tillage in cotton and minimum tillage in wheat than conventional tillage.     

Preliminary observations on effects of tillage systems on soil physical properties, cotton root growth and yield in Gezira Scheme, Sudan

The decline in cotton yields in the Gezira Scheme, Sudan, has been partially attributed to deterioration in soil physical properties and the formation of a plough pan 20 cm deep as a result of the repeated use of the disc plough for land preparation. This field study was conducted during the 1990/91 season at the Gezira Research Station Farm to evaluate the effect of tillage on some soil physical properties of Vertisols, root growth and yield of cotton (Gossypium barbadense L.). Three tillage systems were used: disc harrowing (DH), three bottom disc plough (DP) and subsoiling (SS). Infiltration rates, bulk densities, soil penetration resistance, moisture depletion and root and shoot growth were measured. The results indicated that infiltration rate was not increased significantly by SS. Plant height and shoot dry matter were significantly higher with SS at later growth stages. Bulk density of the plough pan at 135 days after sowing accounted for 90% of the observed variation in subsoil root dry weight while soil penetration resistance accounted for 59% of the variation. Subsoiling increased water use efficiency 25 and 13% over DH and DP respectively. Subsoiling increased cotton yields over DH but the increase over DP was not significant.     

The impact of tillage and residual nitrogen on wheat

Wheat (Triticum aestivum L.) yield and quality is influenced by management of the previous crop but is highly dependent on current year management. The objective of this study was to evaluate the response of winter wheat seeded in two tillage systems [conventional tillage (CT) and no-till (NT)] to four N rates applied to a previous cotton (Gossypium hirsutum L.) crop (0, 67, 134, and 202 kg ha⁻¹). The experiment with wheat was conducted on a Dothan sandy loam (fine, loamy siliceous, thermic Plinthic Kandiudults) at the University of Florida North Florida Research and Education Center near Quincy, FL from 1995 to 1997. For most plant characteristics, there was a tillage x N x year interaction. Greater plant emergence (79.4 vs. 65.3%) and grain N (23.5 vs. 21.5 g kg⁻¹), and lower grain moisture (139 vs. 142 g kg⁻¹) were obtained under NT than CT, respectively, in one out of two years. Nitrogen applied to a previous cotton crop increased wheat grain yields, plant height and seed number under NT in 1995–1996 and CT in 1996–1997, head density under NT in both years, harvest index under CT in 1996–1997, and grain N concentration in 1995–1996 and 1996–1997 due to residual plant and soil N. With every 1 kg N applied to a previous cotton crop, wheat grain yields increased by 5.38 kg ha⁻¹ under NT, whereas grain yield under CT was not influenced by N application to cotton in 1995–1996. In 1996–1997, grain yields increased by 4.96 and 4.23 kg ha⁻¹ for wheat grown in NT and CT, respectively. Generally, wheat seeded in NT following cotton did not decrease stand or yields compared to CT and wheat grain yields and grain N content increased with N fertilization of the previous crop. However, we would have to apply about 134 kg N ha⁻¹ to a previous cotton crop to maximize wheat production under NT and CT.     

Conservation tillage as an approach to enhance crops water use efficiency

Conservation tillage practices great role in improving productivity of water. This study hypothesis that tied-ridging and riding tillage could enhance the yield and water use efficiency. Hence, a field experiment was carried out to investigate their potentiality in improving the water use efficiencies for different crops (cotton, groundnut, sorghum and wheat) compared to basin (control) during two excessive seasons. The experiments were organized in a spilt-plot experimental design. The water use efficacies (WUEs) were examined in term of technical, economical and hydraulic water use efficiencies for the both conservation tillage under irrigated conditions. The results indicated that both the conservation tillage techniques showed positive effect (P?≤?.05) on the WUEs. The tied-ridging gave the highest values of WUEs than ridging for all crops. Moreover, tied-ridging increased the average values of water use efficiency by 75%, 48%, 17% and 85% for cotton, sorghum, groundnut and wheat, respectively, compared to that of control treatment, which significantly differed from the ridging treatment. Accordingly, conservation tillage improved WUE and the capability of soil to keep moisture which is reflected in high crops production. This suggests that there is substantial scope for improving irrigation water use efficiency of crops by adoption of conservation tillage.     

Soil properties, and cotton growth, yield and fibre quality in three cotton-based cropping systems

The effects of three cotton-based cropping systems on soil properties, black root rot severity, and growth of cotton in a Vertisol were evaluated after a series of floods in eastern Australia. The experimental treatments, which had been imposed since 1985, were conventionally and minimum-tilled continuous cotton, and minimum-tilled cotton–wheat rotation. Frequent rainfall and flooding during the winter of 1998 resulted in near saturated soil at spring sowing in October. Although conventional tillage operations were completed before flooding, minimum tillage operations were not possible due to excessive moisture and cotton was sown onto the old beds with no-tillage. Soil specific volume (electrical conductivity of a 1:5 soil:water suspension) EC_1:5, exchangeable Na content, pH and organic C were determined for the top 0.6 m of the profile in summer 1998 and again in 1999. Organic C in the surface 0.10 m was also evaluated during 1998–2000. Black root rot severity and mycorrhizal fungal colonisation were evaluated at 6 weeks after sowing. Tissue nutrient concentrations were measured in mature cotton plants. Cotton lint yield and fibre quality were evaluated after picking and ginning.

In comparison with either minimum- or conventionally tilled continuous cotton, minimum-tilled cotton–wheat rotation had the lowest exchangeable Na content and severity of bacterial black root rot, best surface structure and the highest crop growth, nutrient uptake and lint yields. Subsoil structure was the best with conventionally tilled continuous cotton. The 1998 floods appear to have decreased exchangeable Na and increased soil pH in all treatments. Surface organic C also decreased between 1998 and 2000. Soil structural damage was minimised by avoiding tillage and trafficking in wet conditions. Compared with 1998, average yield decreases in 1999 were of the order of 43%. Cotton lint fibre quality was also poorer in 1999.     

Moisture conservation for rainfed wheat production with alternative mulches and conservation tillage in the hills of north-west India

In the hills of north–west India, maize (Zea mays L.)-wheat (Triticum aestivum L.) is the dominant cropping system. However, rainfed wheat suffers from lack of optimum moisture at sowing. Field experiments were conducted for 3 years on a silty clay loam (Typic Hapludalf) to evaluate the effectiveness of mulches and conservation tillage for rainfed wheat in mitigating this problem. The treatments were ten factorial combinations of five mulch-tillage practices and two nitrogen levels (N₆₀ and N₁₂₀ kg ha⁻¹). Mulch treatments consisted of application of 10 Mg ha⁻¹ (dry weight basis), to previous standing maize, of either wild sage (Lantana camara L.) or eupatorium (Eupatorium adenophorum Sprengel) in combination with either conventional or conservation (minium) tillage prior to wheat sowing. These alternative practices were compared to the conventional farmer practice of soil tillage after harvest of maize with no mulch. The application of these weed mulches to standing maize maintained friable soil structure owing to a five fold higher mean population of earthworms underneath mulch. Mulches resulted in 0.06–0.10 m³ m⁻³ higher moisture in the seed-zone when wheat was sown compared with the conventional farmer practice of soil tillage after maize harvest. Mulch-conservation tillage treatments favourably moderated the hydro-thermal regime for growing a wheat crop. The mean root mass density under these treatments at wheat flowering was higher by 1.27–1.40 times over the conventional farmer practice during the 3 year study. Conservation tillage holds promise because it does not require elaborate tillage and may ultimately reduce animal draught in the hilly regions. Recycling available organic materials having no fodder value coupled with conservation tillage may help enrich the soil environment in the long-term. The practice also offers gainful use of these obnoxious weeds that cause great menace in grass and forest lands in the region.     

Effects of tillage systems in dryland farming on near-surface water content during the late winter period

Tillage systems modify, at least temporarily, some of the physical properties of soil, such as soil porosity. Tillage also has an indirect effect on soil water content throughout the growth cycle, particularly in areas with a Mediterranean climate. This paper presents the results of monitoring the water content in the topsoil (0–0.20 m) of three adjacent plots during February to May cycles starting in 1994–1995 and ending in 1998–1999. Each of the plots had a surface area of 2700 m², an 8% slope and Calcic Cambisol soil. Starting in 1994, three different tillage systems were applied: conventional tillage, which is typical of the area (CT); minimum tillage (MT); and no-tillage (NT). Two vertical 200 mm TDR probes were permanently installed in each plot and measurements were taken every week. The results show that, under an NT system, the soil had significantly higher water content than the other two soil plots. However, this increased quantity of water did not denote increased crop production; on the contrary, these preliminary data point to a decrease in crop production.     

保护性耕作对土壤水分和小麦产量的影响

采用3种稻田保护性耕作栽培模式与传统栽培模式的定位试验,对成都平原稻田小麦季的土壤水分及产量进行了研究。结果表明:小麦全生育期,免耕覆盖处理的土壤含水率明显地高于翻耕覆盖处理,而翻耕不覆盖处理最差;小麦分蘖高峰期,覆盖处理的土壤含水率比不覆盖处理高17.7%～75.9%,免耕覆盖处理的土壤含水率比翻耕覆盖处理高12.7%～41.0%;免耕覆盖处理的小麦最高茎蘖数又比翻耕覆盖处理增加23.8%～72.3%,均极显著优于翻耕处理;覆盖处理的小麦产量比不覆盖处理增产6.3%～19.5%,免耕覆盖处理比翻耕覆盖处理增产3.2%～8.0%。稻田保护性耕作有利于提高成都平原区小麦产量。     

Diversified cropping systems in semiarid Montana: Nitrogen use during drought

Improved nitrogen use efficiency would be beneficial to agroecosystem sustainability in the northern Great Plains of the USA. The most common rotation in the northern Great Plains is fallow–spring wheat. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water and available nitrogen, decreasing the efficiency of fallow. Chemical fallow and zero tillage systems improve soil water conservation, and may improve nitrogen availability to subsequent crops. We conducted a field trial from 1998 through 2003 comparing nitrogen uptake and nitrogen use efficiency of crops in nine rotations under two tillage systems, conventional and no-till. All rotations included spring wheat, two rotations included field pea, while lentil, chickpea, yellow mustard, sunflower, and safflower were present in single rotations with wheat. Growing season precipitation was below average in 3 of 4 years, resulting in substantial drought stress to crops not following fallow. In general, rotation had a greater influence on spring wheat nitrogen accumulation and use efficiency than did tillage system. Spring wheat following fallow had substantially higher N accumulation in seed and biomass, N harvest index, and superior nitrogen use efficiency than wheat following pea, lentil, chickpea, yellow mustard, or wheat. Preplant nitrate-N varied widely among years and rotations, but overall, conventional tillage resulted in 9 kg ha⁻¹ more nitrate-N (0–60 cm) for spring wheat than did zero tillage. However, zero tillage spring wheat averaged 11 kg ha⁻¹ more N in biomass than wheat in conventional tillage. Nitrogen accumulation in pea seed, 45 kg ha⁻¹, was superior to that of all alternate crops and spring wheat, 17 and 23 kg ha⁻¹, respectively. Chickpea, lentil, yellow mustard, safflower, and sunflower did not perform well and were not adapted to this region during periods of below average precipitation. During periods of drought, field pea and wheat following fallow had greater nitrogen use efficiency than recropped wheat or other pulse and oilseed crops.     

Wheel traffic and tillage effects on runoff and crop yield

Traffic and tillage effects on runoff, soil water and crop production under rainfall were investigated over a period of 6 years on a heavy clay vertosols (vertisols) in Queensland, Australia. A split plot design was used to isolate traffic effects, while the cropping program and treatments were broadly representative of extensive grain production practice in the northern grain region of Australia. Treatments subject to zero tillage and stubble mulch tillage each comprised pairs of 90 m² plots, from which runoff was recorded. A 3 m wide controlled traffic system allowed one of each pair to be maintained as a non-wheeled plot, while the complete surface area of the other received a single annual wheeling treatment from a working 100 kW tractor.

Mean annual runoff from controlled traffic plots was 81 mm (36.3%) smaller than that from wheeled plots, while runoff from zero tillage was reduced by 31 mm (15.7%). Traffic and tillage effects appeared to be cumulative, so the mean annual runoff from controlled traffic and zero tillage plots, representing best practice, was 112 mm (47.2%) less than that from wheeled stubble mulch plots, representing conventional cropping practice. Rainfall infiltration into controlled traffic zero tillage soil was thus 12.0% greater than into wheeled stubble mulched soil. Rainfall/runoff hydrographs show that wheeling produced a large and consistent increase in runoff, whereas tillage produced a smaller increase. Treatment effects were greater on dry soil, but were still present in large and intense rainfall events on wet soil.

Plant available water capacity (PAWC) in the 0–500 mm zone increased by 10 mm (11.5%) and mean grain yields increased by 337 kg/ha (9.4%) in controlled traffic plots, compared with wheeled plots. Mean grain yield of zero tillage was 2–8% greater than that of stubble mulch plots for all crops except for winter wheat in 1994 and 1998. Increased infiltration and plant available water were probably responsible for increased mean grain yields of 497 kg/ha (14.5%) in controlled traffic zero tillage, compared with wheeled stubble mulch treatments. Dissipation of tractive and tillage energy in the soil is the apparent mechanism of deleterious effects on the soils ability to support productive cropping in this environment. Controlled traffic and conservation tillage farming systems appear to be a practicable solution.     

The effect of seeding and tillage methods on productivity of rice–wheat cropping system

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.     

Stratification of nutrients in soil for different tillage regimes and cotton rotations

Crop management practices, especially tillage and rotation, can impact soil nutrient stratification, crop growth, and yield. The objectives of this study were to determine the soil-profile distribution of plant-available nutrients in four depth intervals from 0 to 90 cm for different cotton (Gossypium hirsutum L.) cropping systems, tillage regimes, and N fertilization rates in a south-central Texas silty clay loam soil after 5 years of treatment imposition. Distribution of nutrients in the soil profile varied between cropping systems (continuous cotton monoculture and cotton–corn (Zea mays L.) rotation), conventional (CT) and reduced tillage (RT), and N fertilization rates (0, 80, and 160 kg N ha⁻¹). Plant-available P showed the greatest stratification and was 426% higher at 0–15 cm than at 60–90 cm, while SO₄ had the greatest increase (42%) with depth. The percentage decrease from 0–15 to 60–90 cm was 47% and 147% for NO₃ and K, and 76%, 12%, 43%, and 232% for Mn, Fe, Cu, and Zn, respectively. In contrast, Ca and Mg concentrations increased 22% and 15%, respectively, from 0–15 to 60–90 cm. Increasing the N fertilization rate increased plant-available NO₃ and SO₄ but decreased K, Fe, Cu, and Zn concentrations. Inclusion of corn in rotation with cotton decreased plant-available Mn, Fe, and Cu from 15 to 90 cm relative to continuous cotton at 160 kg N ha⁻¹. For unfertilized soil, rotation increased micronutrient concentrations at 15–60 cm compared to continuous cotton. On average, CT cotton–corn had significantly lower K, Ca, Mg, Na, and SO₄ concentrations than CT continuous cotton. Reduced tillage and diversified cropping systems altered the distribution of plant-available nutrients in soil relative to CT and continuous cotton. In fact, RT increased plant-available P and NO₃ in surface soil, which may have contributed to higher lint yields than CT continuous cotton.     

Conservation tillage for soybean in the U.S. Southeastern Coastal Plain

Double cropping of soybean has progressed less rapidly in the U.S. Southeastern Coastal Plains than expected by the ample rainfall and long frost-free season. Post-emergence herbicides, the management of plant residues to reduce water use by cover crops, and a no-till planter with a combination subsoiler are the innovations that have facilitated this new production. Full-season soybean (Glycine max L.) was planted following a grazed cover crop of winter rye (Secale cereale L.) or late-season soybean was planted following winter wheat harvest. In both cases, a special planter was used with an integral subsoil shank ahead of the opener. Full-season soybean under conservation tillage produced yields equal to or better than yields in conventional clean tillage. In a dry summer, soybean yields under conservation tillage exceeded conventional tillage because of suppressed early biomass production which conserved stored soil water and favored growth during the reproduction phase of the crop-cycle. Late-season soybean yields behind wheat favored the conservation tillage practice of in-row subsoil-planting into stubble. However, planting in burned-off wheat stubble produced the highest yields in this study. In a dry spring, the cover crop accelerated soil water use which resulted in lower soybean yields under conservation tillage. Comparisons of 76 vs. 97 cm row spacing were inconclusive, but the trend suggests that wider rows conserve water under periods of drought and that the narrower-row configuration favors adequate water regimes.     

Soil loosening on permanent raised-beds in arid northwest China

Poor lateral water infiltration into permanently raised beds (PRB) can reduce crop yield and water use efficiency (WUE) in dryland agriculture. Especially for densely planted crops the reduced soil moisture affects seedling emergence and causes slow crop growth. Soil loosening with three different types of cutters was tested to overcome this problem of wide PRB in this study. A field experiment with five treatments (traditional tillage, bed without soil loosening, bed with soil loosening by two-edge cutter, bed with soil loosening by flat cutter and bed with soil loosening by V-shaped cutter) was conducted in the Hexi Corridor, northwest China, on spring wheat in 2005 and 2006. The effects of soil loosening and the performances of the three cutters were assessed based on 2 years of soil moisture, bulk density, temperature, spring wheat growth, yield, WUE, power and fuel consumption data. Soil loosening significantly increased lateral water infiltration and thus improved soil water content by 3–8% to 100 cm depth and soil temperature by 0.2–0.4 °C to 30 cm depth compared to beds without soil loosening on sandy-loam soil in 100 cm wide bed systems. Furthermore, bulk density at 10–20 cm depth was about 7.4% lower for bed with soil loosening treatments than for bed without soil loosening. The best results were achieved by the V-shaped cutter, which at a slight additional fuel consumption of 0.46–0.84 l ha⁻¹ offered the greatest benefits to spring wheat yield and WUE. Spring wheat yields increased by 5% and WUE improved by 38% compared to traditional tillage due to higher soil moisture and temperature, lower bulk density and faster growth. The improvements in WUE have tremendous implications in the arid areas of northwest China where agriculture relies heavily on irrigation, but water resources are scarce. We conclude therefore that soil loosening by V-shaped cutter is an efficient way to remove poor water infiltration, and significantly improve yield and WUE for wide beds under PRB farming system in arid areas of northwest China.     

Conservation tillage and optimal water supply enhance microbial enzyme (glucosidase,urease and phosphatase) activities in fields under wheat cultivation during various nitrogen management practices

Field experiments were conducted on sandy clay loam soil at New Delhi, during the winter season of 2007 and 2008 to investigate the effect of tillage, irrigation regimes, i.e. sub-optimal, optimal and supra-optimal water supply, and integrated nutrient management practices (INM) on soil enzymatic activities after cultivation of wheat (Triticum aestivum). Soil glucosidase (54.5%), urease (88.8%), acid phosphatase (97.4%) and alkaline phosphatase (85.3%) activities increased significantly under conservation tillage compared with conventional tillage fields. An optimal water supply (i.e. three irrigations) led to a significant increase in soil enzymatic activity over sub-optimal (i.e. two) and supra-optimal (five) irrigation. Urease activity was slightly lower in the sub-optimal irrigations, but higher in supra-optimal irrigations by 15.5% than in optimal irrigation in conventional tillage. This study suggests that inorganic and organic nutrient combinations with conservation tillage and optimal water supply significantly improved soil enzymatic activities.     

休闲期耕作方式和施用保水剂对旱地小麦产量及水分利用率的影响

为探讨提高旱地麦田休闲期土壤蓄水保水能力、保证旱地小麦稳产高产的有效途径,本研究采用双因素裂区试验,主区为耕作方式(深松、深翻和旋耕),副区为保水剂施用量(0、45、90 kg·hm^-2),研究了耕作方式和施用保水剂对土壤含水量、土壤养分、旱地小麦产量和水分利用率的影响,并分析了土壤含水量、生育期耗水量与旱地小麦产量及其构成因素和水分利用率之间的相关关系。结果表明,与休闲期旋耕相比,休闲期深松提高了播前20~160 cm土层的土壤含水量,休闲期深翻提高了播前0~20 cm和60~140 cm土层的土壤含水量,加速了收获期20~200 cm土层的水分利用;并通过增加穗数和穗粒数使旱地小麦产量分别提高了12.63%和6.88%,显著提高了水分利用率和降水利用率,20~40 cm土层有机质、碱解氮、速效磷含量总体提高。休闲期耕作,配施保水剂45 kg·hm^-2显著提高了旱地小麦休闲期蓄水保水能力、水分利用率和产量。休闲期深松增产效果和提高水分利用率效果优于休闲期深翻。旱地小麦产量和降水利用率与播前60~120 cm土层含水量呈正相关。本研究结果为晋南旱地小麦优化耕作方式和保水剂施用量提高产量和水分利用率提供了理论依据,对旱地小麦稳产高产、减小年际间产量波动具有重要意义。     

An evaluation of controlled traffic with reduced tillage for irrigated cotton on a Vertisol

Where Vertisols are used for the mechanised production of irrigated cotton, the main pre-planting tillage options are ‘direct listing’ (a ‘controlled traffic-reduced tillage’ treatment with retained ridges), deep ripping (0.45 m deep) and chisel ploughing (0.25 m deep). An experiment was established, on a commercial scale under furrow irrigation, to compare the effects of these treatments on the physical properties (aeration, strength and water content) of a frequently irrigated Vertisol over 3 years. The growth and profitability of three cotton crops and one wheat crop were monitored during this period. The soil was well structured when the experiment commenced. Soil measurements showed that whilst the deep ripped treatment had lower resistance to penetration than the direct listed treatment, it provided a less favourable environment for root growth than the direct listed soil due to prolonged waterlogging after irrigation. An excess of water entered the ripped profile under the prevailing irrigation regime. All treatments had a sodic subsoil that was poorly drained. The chisel ploughed treatment generally behaved in a fashion that was intermediate between the direct listed and deep ripped treatments. The direct listed treatment resulted in higher cotton lint yields and lower land preparation costs, in comparison with deep ripping. Profitability increases were of the order of 11% when the lint value was 1.78 Australian dollars kg⁻¹. The deep ripped soil had more stored water than the other treatments throughout each irrigation cycle, but this potential advantage could not be expressed in terms of better crop yield and improved water use efficiency. A supplementary experiment is needed to evaluate the three tillage options where irrigation water is applied less frequently.     

Effect of Irrigation Amount and Tillage System on Yield and Water Use Efficiency of Cowpea

Abstract

Yield, water storage, and water use efficiency of irrigated cowpea (Vigna unguiculata L. Walp) were evaluated under four tillage systems and five irrigation regimens. The tillage systems are conventional tillage, reduced tillage, zero tillage, and manual tillage, and the irrigation regimens were created by using a line source sprinkler system. Reduced and conventional tillage produced higher yield and water use efficiency than zero and manual tillage (p<0.05). Reduced tillage produced the highest yield of 1.88 t/ha and had slightly higher yields than conventional tillage in the first four irrigation levels because of higher water storage and lower percolation than conventional tillage. Although manual tillage had high water storage and low percolation, the water was not beneficially used probably because of high evaporation leading to significantly (p<0.05) high soil moisture tension before irrigation. Zero tillage, on the other hand, resulted in significantly (p<0.05) lower application efficiency due to higher runoff. Therefore, irrigated land requires some forms of mechanical tillage or water conservation measures for manually tilled land for improved water use efficiency.     

Diesel and glyphosate price changes benefit the economics of conservation tillage versus traditional tillage

Recent increases in diesel price and decreases in glyphosate [N-(phosphonomethyl) glycine] price should favor the profitability and farmer acceptance of herbicide-intensive conservation tillage systems versus fuel-intensive traditional tillage (TT) systems. Profitability results from a long-term field experiment that compared TT, minimum tillage (MT), and delayed minimum tillage (DMT) systems for winter wheat–(Triticum aestivum L.)summer fallow in eastern Washington, USA were calculated using both 1998 and 2005 input prices. Net returns for the MT and DMT systems increased by US$ 6.37 and 6.30 (rotational ha)⁻¹, respectively, and net returns to the TT system decreased by US$ 2.36 (rotational ha)⁻¹ when 2005 versus 1998 prices were used. Here, rotational ha equals 0.5 ha fallow and 0.5 ha wheat. Focusing on the dominant crop of soft white winter wheat (SWWW), the 2005 price hikes pushed diesel costs up for all systems, from US$ 6.81 (rotational ha)⁻¹ for DMT to US$ 9.00 (rotational ha)⁻¹ for TT. The cost of diesel for the conservation tillage systems, relative to the cost for TT, decreased by US$ 1.50–2.20 (rotational ha)⁻¹. The conservation tillage systems accrue greater savings from the price reduction in glyphosate because they consume more of this herbicide. An unanticipated result was that relative cost savings from price changes in N fertilizer rivaled those from diesel and glyphosate because anhydrous NH₃–N was exclusively used in the experiment for TT and aqueous NH₃–N for MT and DMT. The price of anhydrous NH₃–N increased from US$ 0.55 kg⁻¹ in 1998 to 0.85 kg⁻¹ in 2005, a 56% increase. Aqueous NH₃–N only increased from $0.75 kg⁻¹ in 1998 to 0.85 kg⁻¹ in 2005, a 15% increase. The greater price increase for anhydrous NH₃–N penalized the TT system because of its use of this fertilizer. If the same source of N fertilizer were used on all three tillage systems, this fertilizer cost effect would disappear. Nonetheless, the conservation tillage systems still retained a statistically significant profitability advantage over TT even if the same fertilizer was used throughout. The sharp price increase for diesel and the concurrent price decrease for glyphosate herbicide favored the conservation tillage systems over TT in this study. Results provide strong evidence for the superior profitability of conservation tillage winter wheat–summer fallow under current economic conditions.     

Analysis of mechanized cotton cultivation practices under dry land and irrigated conditions

A survey was carried out to study the various local practices developed for cotton culture throughout Israel, to locate the operations which could be deleted or replaced by other operations, and to determine the relative yield dependence on tillage and irrigation. Energy inputs consume about 1/6 to 1/4 of the gross returns for irrigated cotton, but their effects on yields could not be discerned. However, water application through precipitation and irrigation were found to have a large effect on yield.To reduce soil compaction hazards, energy input and labor costs, a new precision-minimum tillage procedure was developed and tested. Between the conventional and the new practice no significant differences in yield could be distinguished, provided there was no blockage of the planter by cotton stalks which caused an uneven stand. However, by precision-minimum tillage, energy input during autumn was cut by approximately one half, and the total mean energy input was reduced by one third.