Mechanical Tillage Research Articles

Harvesting Systems, Soil Cultivation, and Nitrogen Rate Associated with Sugarcane Yield

The adoption of mechanical harvesting of green cane gives rise to concerns as to whether systems developed under burnt cane harvesting are applicable to a green cane harvesting system. In particular, tillage, which is an integral part of the burnt cane system, may no longer be necessary, and the nitrogen fertilizer rates required may need to be replaced due to the large amounts of organic matter being returned to the soil after green cane harvesting. Mechanical harvesting is relatively new in Brazil and little is known about its effect on other sugarcane production strategies. This work aimed to evaluate sugarcane performance under not only different harvesting and cultivation systems, but also different nitrogen fertilizer rates over a 3-year period. The experimental design was a split plot with harvesting systems (burnt vs. green) as main plots, cultivation (interrow vs. no cultivation) as sub plots, and nitrogen rates as sub-sub plots. The harvesting systems produced similar sugarcane yields throughout the experimental period, which demonstrates that the harvest systems do not influence sugarcane yield. Mechanical tillage practices in interrow after harvesting had no impact on stalk yield or sugar quality, indicating no necessity for this operation in the following crop. Ratoon nitrogen fertilization promoted an increase of stalk and sugar yield, with highest yields obtained at the rate of 130 kg ha−1 N. However, there was no interaction between harvesting system and nitrogen rate.

Наукові основи точного механічного обробітку ґрунту і перспективи його впровадження в Україні

Precision mechanical tillage is a fundamentally new agricultural strategy of farming, which is based on the use of information technology and new technical means and involves the implementation of technological measures for the main and pre-sowing tillage, taking into account the spatial heterogeneity of the physical properties of the root-content layer as indicators of differentiation of field tillage. In the article were presented the main provisions and stages of the method of determining the soil spatial heterogeneity of the plot. It was characterized indicators of precision mechanical soil tillage and promising methods for measuring parameters for precision tillage, including technical and software. It was proposed the preliminary norms of the physical properties of the treated layer for substantiation of the intensity of the basic mechanical soil tillage. It was proposed the characteristic of the main stages of the transition to precision farming and the mechanisms that should ensure its effective functioning, it was calculated the expected economic efficiency of precision farming. In the article was analyzed the spatial heterogeneity of arable land of Ukraine in terms of basic physical characteristics (structure, bulk density and penetration resistance) in the crop layer and plow sole. Some general patterns of manifestation of the spatial heterogeneity of the investigated properties of the soil cover of the land plots and the crop in all natural zones of Ukraine are analyzed, it serving as the main argument for the transition from generalized zonal technologies to precision mechanical tillage. The baseline data for the technological substantiation of the development of precision tillage (according to the content of the blocks in the seed layer) was worked out. Prospects for the introduction of precision agriculture in Ukraine are considered, based on the successful experience of mastering precision farming systems. Key words: soil, precision tillage, spatial heterogeneity, physical properties.

Comparative Programs for Arthropod, Disease and Weed Management in New York Organic Apples.

Organic apple production in the eastern US is small and is mostly based on existing varieties, which are susceptible to scab, and rootstocks, which are susceptible to fire blight. This requires numerous sprays per year of various pesticides to produce acceptable fruit. From 2014 to 2016, we tested different arthropod, disease and weed management programs in an advanced tall spindle high-density production system that included disease-resistant cultivars and rootstocks, in an organic research planting of apples in Geneva, New York. Arthropod and disease management regimens were characterized as Advanced Organic, Minimal Organic, or Untreated Control. Results varied by year and variety, but, in general, the Advanced program was more effective than the Minimal program in preventing damage from internal-feeding Lepidoptera, plum curculio, and obliquebanded leafroller, and less effective than the Minimal program against damage by foliar insects. Both organic programs provided comparable control of sooty blotch, cedar apple rust, and fire blight, with some variability across cultivars and years. The advanced selection CC1009 and Modi seemed to possess complete resistance to cedar apple rust, while Pristine had partial resistance. For weed control, bark chip mulch, organic soap sprays, and limonene sprays tended to be most effective, while mechanical tillage and flame weeding had lower success.

Efficiency of the use of herbicides in soybean crops under various farming systems

Privedey results of investigations, a soil and the effect of herbicides on the insurance reserve of moisture in the soil and contamination of crops of soybeans in traditional cropping system and No-till. It is established that the rejection of mechanical tillage positive effect on the moisture content of soybean throughout its growing season. The use of chemical protection from weeds, including the introduction of tank mixtures of herbicides before germination, and during the growing season of culture, ensures reliable control of weeds. The combination of No-till and reliable system of weed control provides higher soybean yields than the traditional system of agriculture.

Сезонна динаміка щільності складення чорнозему опідзоленого західного Лісостепу України за різного використання в агроценозах

Soil as multicomponent organized and complex ecosystem has a number of important ecosystem functions. Fertility is the most integrated of it, which is directly connected with all the functions and properties of the soil and is the result of effective cooperation. Thus, essential for optimal functioning of soil fertility is implementing its agrophysical properties that are the basis of the formation of high and stable crops yields. A special place to optimize the agrophysical properties takes soil structure density, which is the most objective and comprehensive summary measure. This statement came through the work of Y. B. Revuta, and his followers. These works had significant impact on the soil science development; thru bulk density peoples began to assess soil physical condition and its changes due to human impact. Soil compaction is the main reason of it productivity reducing. Plants feel strong anoxia when soil density index falls below 15%. Over compaction reduces soil biological activity, including nitrification, total number of cellulose destructors and actinomycetes. Soil density increase in 0.1 g/cm3 compared to an optimum – course crops yield reduction by 15-20%, and 0.2 g / cm3 - 50%. Soil structural condition, bulk density, water-physical properties, crop productivity are largely dependent on its tillage type, nutrient management in crop rotation. Tillage (especially deep plowing) and fertilization significantly change the natural structure of black soil. Thus, the result of years of plowing at the same depth a dense plow sole is formed. It affects many soil processes, especially in water, temperature and soil gas regime. V. D. Mukhas’ found that one of the main signs of land degradation indicators are bad soil structure and density structure of the soil during the growing season. Vladimir Medvedev says’ that mechanical tillage and soil structural changes caused by it are the main reason of water-physical properties degradation in arable land. Fedorovskyi D.V. notes’ that high soil density make soil water and nutrients unavailable for plants. Wheat roots do not penetrate into the layers of soil with a density of 1.65, roots of vegetables - 1.45 g / cm3. Apple trees are not durable if there is compaction layer under 1.55 in 2 meter layer of medium loamy soil, and more than 1.30 g/cm3 on clay soils. Kopytko P.G. indicates that density of soil with loamy texture (20-80 cm layer) in root zone under highly productive apple orchards is around 1.2-1.3 g/cm3. Therefore, these figures can be considered as an optimal for the functioning of the root system and fruit crops nutrition. In particular, it is known that manure as an organic improves soil physical, chemical, agrophysical properties and humus regime. Nowadays manure becomes irrelevant from economic point of view. Therefore against the backdrop of rising rates agrotehnogenesys in the literature there are more and more reports of adverse changes in the properties of soils under the influence of mineral fertilizers. Thus, G.V. Dobrovolsky indicates that fertilizer even in small doses lead to dispersion structure, reduced agrigates strength, reducing the visible poroznosti and increase bryluvatosti (Dobrovolski, 1983). That is why additional study of the effect of different soil tillage and nutrition plans on podzolic chernozem bulk density in different soil-climatic and farm specific conditions is needed.

Review on Impact of Climate Change on Weed and Their Management

The global climate is changing; along with measuring temperature and CO2 level changes that are considered major drivers of climate change, there is also increasing attention being given to its impact on agricultural production systems (including weeds). Climate conditions exert a significant influence on the spread, population dynamics, life cycle duration, infestation pressure and the overall occurrence of the majority of agricultural pests. Weeds are among the agricultural pest that can be influenced by climate change. It is expected that climate change will bring about a shift in the floral composition of several ecosystems at higher latitudes and altitudes, as changes in temperature and humidity will be reflected on flowering, fruiting and seed dormancy. Changes in atmospheric CO2 levels, rainfall, temperature and other growing conditions will affect weed species ‘distribution and their competitiveness within a weed population and within crop. Any factor which increases environmental stress on crops may make them more vulnerable to attack by insects and plant pathogens and less competitive with weeds. Many of these weeds reproduce by vegetative means and recent evidence indicates that as a group, these weeds may show a strong response to recent increases in atmospheric CO2. Changing and increment of temperature is one main characteristics of climate change which may affect existing plants (weeds shift) and allow some other plants (weeds) to replace native and will be expand in to new areas which is not existed before. Even under drought condition some weeds produce allele-chemical that made weeds to thrive well and compete with crop. An increase in root: stem, with increases in the growth of roots or rhizomes, particularly of perennial weeds, may make it harder to control some weeds that regrow from root fragments left after mechanical tillage. The direct impacts of climate change will be either on the biology of the biological control agent and/or on the ability of the host plant to resist, tolerate or compensate for the presence of the herbivore or plant pathogen. Increased temperature would be expected to increase the rate of life cycles of both the biological control agents and the weeds. Increased water stress will affect the host plant’s development, and through this, the development of biological control agents, so they might be less effective in drier situations.

Short-term soil loss by eolian erosion in response to different rain-fed agricultural practices

Eolian (wind) erosion is a widespread process and a major form of soil degradation in arid and semi-arid regions. The present study examined eolian soil loss and changes in soil properties at a field scale, in response to different soil treatments in two rain-fed agricultural practices by short-term field experiments using a boundary-layer wind tunnel and soil properties analysis. Two practices with different soil treatments of mechanical tillage and stubble grazing intensities were applied in the fallow phase of the rotation (dry season). Mechanical tillage operations and stubble grazing intensities had immediate and direct effects on soil aggregation but not on the soil texture, and the contents of soil water, organic matter, and CaCO3. Higher erosion rates, measured as fluxes of total eolian sediment (TAS) and particulate matter <10μm (PM10), were recorded under mechanical tillage and grazing intensities compared with the undisturbed topsoil of the control plots. The erosion rates were higher in grazing plots than in tillage plots. The calculated soil fluxes in this study indicate potentially rapid soil degradation due to loss of fine particles.

The evolution of podzolized and regraded chernozems in Eastern Upland Wooded Steppe of Ukraine and the ways of their development

It is indicated that podzolized and regarded chernozems in moderately humid and arid zones of Left-bank Wooded steppe with HTC 1,2–1,0 (within the valleys of the Sula and Oskil rivers) occur in high watersheds along right bedrock banks of the valleys, adjoining or being included into wooded refugiums. Being formed by the grove biogeocenosis, they have high rates of fertility. The morphological research of natural podzolized chernozems profiles showed, that the upper humus slightly-eluviated horizon, densely interweaved by roots, has coarse agronomically valuable structure, loose composition, dark-grey colour, that indicates high content of humus. It is mostly favoured by the biologically active, rich in calcium ground litter and the pristinity of soil texture. The general capacity of the humus profile is not less than 100 cm. While brining natural soils into tillage some changes of soil development conditions arise. They are: hydrothermic conditions, secondary carbonate enrichment (regradation), loosening of illuvial horizon. Under mechanical tillage the granular structure changes into a pulverescent and cloddy one, the topsoil becomes lighter because of humus loss, though the humus profile becomes 10–20 cm deeper. The analytical results indicate the sufficient differences in physicochemical and agrochemical characteristics between forest podzolized chernozems and their regradated analogs in tillage. Natural soils contain 5,7–6,5 % of humus in upper 0–35 cm layer, and up to 10,0 % in 0–15 cm layer. They also have considerable resources of hydrolyzable nitrogen. In agrogenic soils the humus content is up to 3,6 %. The humus is of a humate type both in podzolized and regarded soils. The smallest proportion of Сh.a./Сf.a is in the lower layer of humus eluviated horizon of forest soils. The level of humus loss by agrogenic soils in humus slightly-eluviated layer fluctuates from 37 % to 44 %. Dark-grey and grey forest soils lose more than half of humus content, typical chernozems – nearly 30 %, ordinary chernozems – 20 %. Regraded analogs are inferior according to the hydrolyzable nitrogen content. Positive evolutional changes in tillage, such as acidity reduction, bases saturation growth, illuvium destruction, didn’t yield expected results – resistance to degradation processes. For the development of agrogenic soils it is necessary to implement flexible complex systems of husbandry with minimal intensity of tillage, adapted to the landscape, bringing the culture of husbandry closer to natural conditions. Promising is the implementation of soil protection technologies with the maximum use of freak produce of plant growing. The integrity of soil composition and biologically active layer of mulch create the conditions, close to virgin ones, that lead to the transition of soil to natural non-degradation conditions without losing its productive functions.

EFFECT OF SOIL TILLAGE AND PLANT RESIDUE ON SURFACE ROUGHNESS OF AN OXISOL UNDER SIMULATED RAIN

Surface roughness of the soil is formed by mechanical tillage and is also influenced by the kind and amount of plant residue, among other factors. Its persistence over time mainly depends on the fundamental characteristics of rain and soil type. However, few studies have been developed to evaluate these factors in Latossolos (Oxisols). In this study, we evaluated the effect of soil tillage and of amounts of plant residue on surface roughness of an Oxisol under simulated rain. Treatments consisted of the combination of the tillage systems of no-tillage (NT), conventional tillage (CT), and minimum tillage (MT) with rates of plant residue of 0, 1, and 2 Mg ha-1 of oats (Avena strigosa Schreb) and 0, 3, and 6 Mg ha-1 of maize (Zea mays L.). Seven simulated rains were applied on each experimental plot, with intensity of 60±2 mm h-1 and duration of 1 h at weekly intervals. The values of the random roughness index ranged from 2.94 to 17.71 mm in oats, and from 5.91 to 20.37 mm in maize, showing that CT and MT are effective in increasing soil surface roughness. It was seen that soil tillage operations carried out with the chisel plow and the leveling disk harrow are more effective in increasing soil roughness than those carried out with the heavy disk harrow and leveling disk harrow. The roughness index of the soil surface decreases exponentially with the increase in the rainfall volume applied under conditions of no tillage without soil cover, conventional tillage, and minimum tillage. The oat and maize crop residue present on the soil surface is effective in maintaining the roughness of the soil surface under no-tillage.

FIELD PERFORMANCE OF SEVERAL HYBRID ROOTSTOCKS WITH SIX PEACH CULTIVARS

Within the framework of a nationally co-ordinated program supported by the Italian Ministry for Agricultural and Forestry Policy, in the autumn of 2009, a trial was established in the Latium Region (Rome, 41.7888N, 12.5685E, 125 m a.s.l.), on the peach cultivars ‘Ghiaccio’ 1, ‘Romestar’, ‘Sagittaria’, ‘Ufo’ 4, peach selection ‘CE 126’ and nectarine selection ‘CE 124’ grafted onto hybrid Prunus rootstocks: ‘GF677’ (P. persica A— P. amygdalus), ‘Ishtara’ (P. cerasifera A— P. salicina) A— (P. cerasifera A— P. persica); ‘Barrier 1’ (P. persica A— P. davidiana); ‘Cadaman’ (P. persica A— P. davidiana); ‘Felinem’ (P. amygdalus A— P. persica). The experimental design was a randomised complete block with four trees for each cultivar and rootstock, replicated three times. The planting distance was 4.5 x 4.0 m and the trees were trained to a free open vase. The soil, classified as clay loam, had previously grown cereal crops. Weed control was achieved by mechanical tillage between rows and chemical spray along the row. A drip irrigation system guaranteed regular water availability. Considering the average trunk cross-sectional area in the different cultivar/graft combinations, ‘Felinem’ (138.9%), ‘Barrier1’ (119.6%) and ‘Cadaman’ (102.1%) were more vigorous than ‘GF 677’ (100%), while ‘Ishtara’ was weaker (52.0%). The highest yields were induced by ‘Felimen’ (105.3%) and ‘Barrier1’ (103.5%) followed by ‘GF677’ (100%), ‘Cadaman’ (95.7%), and ‘Ishtara’ (49.2%). Trees on ‘Cadaman’ and ‘Barrier1’ roots consistently produced the largest individual fruits, which were the smallest on ‘GF677’.

Modern Tillage and Integrated Nutrient Management Practices for Improving Soil Fertility and Productivity of Groundnut (&lt;i&gt;Arachis hypogaea&lt;/i&gt; L.) under Rainfed Farming System

The field experiment was conducted with four tillage and three nutrient management practices at Agronomy field unit, University of Agricultural Sciences, GKVK, Bangalore, Karnataka, India. The results of the study indicated that, higher groundnut pod yield (1307 and 1282 kg ha-1) and haulm yield (2733 and 2889 kg ha-1) was recorded with mechanical tillage + two intercultivations and integrated application of 50% organics and 50% inorganics, respectively as compared to rest of the treatments. Further, the same treatments noticed higher availability of N, P2O5 and K2O in soil after harvest of groundnut, but greater improvement in soil organic carbon content was observed with conventional tillage + one intercultivation (0.62%) as compared to rest of the tillage practices. The maximum net returns and benefit-cost ratio was recorded with mechanical tillage + two intercultivations (Rs. 11,287 ha-1 and 1.75, respectively) and integrated application of 50% organics + 50% inorganics (Rs. 10,462 ha-1 and 1.69, respectively). However, interaction effect of tillage and nutrient management practices were not influenced significantly on soil fertility and productivity of groundnut under rainfed farming system.

Modern Tillage and Integrated Nutrient Management Practices for Improving Soil Fertility and Productivity of Groundnut (&lt;i&gt;Arachis hypogaea&lt;/i&gt; L.) under Rainfed Farming System

The field experiment was conducted with four tillage and three nutrient management practices at Agronomy field unit, University of Agricultural Sciences, GKVK, Bangalore, Karnataka, India. The results of the study indicated that, higher groundnut pod yield (1307 and 1282 kg ha-1) and haulm yield (2733 and 2889 kg ha-1) was recorded with mechanical tillage + two intercultivations and integrated application of 50% organics and 50% inorganics, respectively as compared to rest of the treatments. Further, the same treatments noticed higher availability of N, P2O5 and K2O in soil after harvest of groundnut, but greater improvement in soil organic carbon content was observed with conventional tillage + one intercultivation (0.62%) as compared to rest of the tillage practices. The maximum net returns and benefit-cost ratio was recorded with mechanical tillage + two intercultivations (Rs. 11,287 ha-1 and 1.75, respectively) and integrated application of 50% organics + 50% inorganics (Rs. 10,462 ha-1 and 1.69, respectively). However, interaction effect of tillage and nutrient management practices were not influenced significantly on soil fertility and productivity of groundnut under rainfed farming system.

Soil conservation and ecosystem services

Accelerated soil erosion, driven by anthropogenic activities such as conversion of natural ecosystems to agroecosystems and mechanical tillage, has numerous adverse impacts on ecosystem services. In addition to degrading soil quality and reducing agronomic/biomass productivity on-site through a decrease in use-efficiency of inputs, off-site impacts of accelerated erosion include eutrophication and contamination, sedimentation of reservoirs and waterways, and emissions of greenhouse gases (e.g., CO2, CH4 and N2O). While advancing food and nutritional security, adoption of restorative land use and recommended management practices are important to strengthening numerous ecosystem services such as improving water quality and renewability, increasing below and above-ground biodiversity, enhancing soil resilience to climate change and extreme events, and mitigating climate change by sequestering C in soil and reducing the emission of CO2, CH4 and N2O. An effective control of accelerated erosion is essential to sustainable development and improving the environment.

Carbon status and structural stability of soils from differing land use systems in the Kingdom of Tonga

AbstractMaintenance of soil carbon stocks is vital for the environment at large and for maintenance of soil chemical, physical and biological fertility. Tonga represents a country in agricultural transition from subsistence to commercial production and whilst this is good for the national economy the impact on soil resources is less clear. The major cropped soils, fallow vegetation types and forest systems of Tonga were identified in each island group and samples of representative soils (0.15 m depth) from each land use unit were taken. Total carbon (CT) and δ13C were measured and labile carbon (CL) determined by oxidation with 333 mm KMnO4. These data were used to determine the carbon management index (CMI) and the proportion of carbon from C4 species in the CT pool. Relative to primary forest, the soil CT and CL generally declined with changes in vegetation and more intense mechanical tillage. The contribution of C4 plants to soil C increased with intensity of mechanical tillage and the prevalence of C4 guinea grass (Panicum maximum Jacquin) fallow. The changes in soil C were reflected in the CMI, and CL was a more sensitive indicator of change than CT. These data indicates that all land use systems have experienced a large net loss of soil C relative to the forest systems. Soil mean weight diameter (MWD) decreased significantly with increased intensity of mechanical tillage and to a lesser extent with the intensity and length of cropping. The relationship between soil MWD and soil C was similar with soil CT and CL. Grass fallow was as effective as permanent vegetation systems in improving soil MWD and lowering the micro‐aggregate (&lt;125 μm) fraction.

Influence of soil management on soil physical characteristics and water storage in a mature rainfed olive orchard

Mechanical tillage represents the most common technique of soil management in olive orchards within the Mediterranean Basin. Such practice may result in soil structure degradation which can significantly reduce water infiltration causing runoff and erosion processes. An alternative opportunity is given by the use of cover crops which eliminates most of the disadvantages of conventional tillage. An experiment was carried out from 2007 to 2009 in a mature and rainfed olive grove located in Southern Italy with the aim to evaluate the effect of different soil management techniques on soil structure and soil water content and storage along the profile. The experimental site was characterised by a slope gradient ranging from 0 to 16%. Since 2000, the olive grove was subjected to two different management systems: sustainable system, SS (no-tillage, spontaneous vegetation cover, annual recycling of pruning material) and conventional system, CS (tillage, no recycling of pruning material). Modifications of soil structure induced by the two different management systems were quantified by micromorphometric analysis of macroporosity. Soil hydrological behavior was determined by field saturated hydraulic conductivity (Ksat) measurements. Soil water content was measured at 10/15-day intervals by gypsum resistivity blocks placed in flat and steep areas (summit, backslope, and footslope) of both systems at different soil depths (25, 50, 75, 100, 150 and 200cm).In the SS soil macroporosity was not very high (about 10%) but homogeneously distributed along the profile which favored the vertical water movement down to deeper horizons. In the CS the occurrence of soil crusting and of compacted layers along the profile hindered infiltration and percolation of rainfall water influencing the soil water content below the 100cm layer. The SS was able to better store water from rainfall, received during the autumn–winter period, especially in the deepest soil layer (from 100 to 200cm). This was evident especially in the steep area at the summit position, where the water amounts stored by SS were 45 and 17% higher than those retained by the CS in 2007 and 2009, respectively. During summer such reserves were available for the olive root systems which usually, under the driest conditions, explore the deep soil zone in search of water. Under our experimental conditions, no yield reduction was observed due to the prompt mowing of the spontaneous cover crops. Therefore, the suitable use of cover crops should be communicated to the olive farmers and strongly recommended within agricultural policy strategies for its evident agronomical and environmental benefits (increase of soil organic carbon, soil structure improvement, reduction of soil and water losses, carbon sequestration).

Variation in major indices of typical black soil fertility under the effect of various agrotechnical methods

It has been demonstrated that continuous use of various kinds of basic tillage treatments and fertilizers is accompanied by decrease in the humus content and the activity of enzymes participating in the cycle of major biogenic elements, such as carbon, nitrogen, and phosphorus. Protease and urease activities appeared to be the most sensitive to the mechanical tillage and fertilizer load. It was concluded that the necessary condition in agrotechnology, such as the usage of organic fertilizers, can promote keeping the content of humus at the level of average values and regulate the activity of enzymes in nitrogen exchange.

Soil physical properties of selected soil series in relation to compaction and erosion on farmers’ fields at Abeokuta, southwestern Nigeria

This study evaluated physical properties of selected soil series and their implications on the soil compaction and erosion in Abeokuta, southwestern Nigeria. Daily rainfall data (1999–2007) were collected to estimate the rainfall erosivity. Seven soil series (Iwo, Iseyin, Ekiti, Jago, Okemesi, Apomu, and Egbeda) were sampled from 0–15, 15–30, and 30–50 cm depths for particle size distribution, organic carbon, pH, upper plastic limit, and compactibility (Proctor test). Microtopographical changes along and across toposequences of two farmers’ fields cleared mechanically and manually, respectively, were monitored using the erosion pin method. Mean annual erosivity (EI30) was high (7646 MJ mm ha−1 hr−1). Particle size, organic carbon, and pH were similar (p ≥ 0.05), while upper plastic moisture was ≤ 2% among different soil series. Soil-moisture density curves indicated a maximum bulk density of 1.77–1.99 g cm−3 for a moisture range of 7.6–14%; while the soils were prone to compaction at low moisture content. Microtopographic changes were found between –2 and 0 cm and –8 and –2 cm on mechanically and manually cleared farmland, respectively. Spatial dependence showed that the soil erosion could be predicted within 5–8 m distance. To avoid erosion and compaction, soil water content should be less than 7.6% before the introduction of mechanical tillage.

Wheat Production Simulation Based on the ALMANAC Model of North China Region

&lt;p&gt;Wheat (&lt;em&gt;Triticumaestivum&lt;/em&gt;) is one of the world's three major food crops, whose production is related to regional food security issues. Studies have shown that technological progress and climate change have a significant impact on wheat yield. We selected North China region as the study site because it is the main producer of wheat and because it experiences active climate change. Using the Agricultural Land Management Alternatives with Numerical Assessment Criteriamodel and statistical analysis method, the following factors were considered to determine the dominant factor that affects wheat production: temperature, precipitation, sunshine, and other climatic factors, mechanical power, irrigation area, chemical fertilizer amount, reservoir total storage capacity, and other technical factors.Results showed that wheat productionis affected by both climatic and non-climatic factors in North China region. Increased temperature has a positive impact on wheat production, whereas reduceds unshine has a negative effect. Warm and dry climate trends areconducive to wheat production. Mechanical tillage and fertilization, irrigation, and water conditions are conducive to the production of wheat, among which water condition has the most significant effect onwheat yield improvement. Compared withthe effects of climaticfactors, those of technical factors are more obvious and direct. In the premise of guaranteed technical conditions, the impactof climate changeonwheat production is more evidentindeveloped areas. Underdeveloped areas of wheat production are more dependent on technological progress; in particular, they rely on the use of chemical fertilizers.&lt;/p&gt;&lt;p&gt; &lt;/p&gt;

Tillage and varietal impacts on tomato (Solanum lycopersicum L.) production on an ultisol in central Cameroon

Across Africa the production of high value horticultural crops is being recognized as a possible route out of rural poverty. To determine at which level of intensification tomato yields were maximized and which tomato cultivar responds best to intensification, an on-farm, factorial trial was conducted at Essong Mintsang in the central region of Cameroon on a rhodic Kandiudult. Current farmer practice of manual tillage yet not destumped was compared with either reduced input (no tillage, not destumped) or increased input (no tillage yet destumped, manual tillage and destumped, mechanical tillage and destumped). Yields and yield components of three tomato varieties were determined to assess if changes in intensity of land preparation can improve soil physical properties and thus yields. At 6 weeks after planting, cultivar Rossol had more flowers (521,126ha−1, p=0.09) than cv. Rio Grande (403,930ha−1), with cv. Roma (504,718ha−1) not being significantly different from either variety. At harvest, across land preparations the cv. Rossol produced higher yields (8.12Mgha−1, p=0.005) than cv. Roma (6.05Mgha−1) and cv. Rio Grande (4.46Mgha−1); the latter being significantly different (p=0.03) from both others. Tomato total and marketable yields were significantly higher in the destumped tractor till, destumped manual till and stumps-retained manual till treatments than in the stumps retained no-till treatment. Yields in destumped no-till treatment were not significantly different from any of the treatments. Total fresh yields of cvs Roma and Rossol increased when the soil was tilled, while cv. Rio Grande had no response to land preparation. Tomato pest and disease damages were not affected by land preparation. Weeding took less time (p=0.05) in destumped manual till (153hha−1) and tractor till (157hha−1) than in not destumped manual till plots (243hha−1). Soil aggregates were least stable in the destumped, tractor till treatment, with significantly lower MWD (p=0.02), and higher mesoaggregate proportions (p=0.05) than in the other treatments. Across tomato cultivars and treatments, the marketable fruit yield could be predicted by clay, macroaggregates and bulk density in the 0–10cm layer: marketable yield=0.12 clay−0.14 macroaggregate+12.20 (with r2=0.50, n=15, p=0.016) and for the 10–20cm soil layer: marketable yield=0.17 clay+5.15 bulk density−10.25 (with r2=0.58, n=15, p=0.005). Early flowering and fruit production combined with nematode resistance were probably the main contributing factors to the high yields of cv. Rossol.

Aggregate C depletion by plowing and its restoration by diverse biomass-C inputs under no-till in sub-tropical and tropical regions of Brazil

Encapsulation of soil organic carbon (SOC) within aggregates is one of the principal mechanisms for long-term C sequestration, macroaggregate formation and stabilization. Our objectives were to quantify the changes in aggregate size distribution, aggregate-C concentrations and stocks upon conversion of native vegetation (NV) to conventional plow-based tillage (CT), and to assess the rate of aggregation and SOC recovery with no-till (NT) under diverse biomass-C inputs. The study was conducted at both sub-tropical (Ponta Grossa – PG, State of Paraná) and tropical (Lucas do Rio Verde – LRV, State of Mato Grosso) sites in Brazil. The SOC content under NV was used as a baseline to evaluate the depletion rate under CT and the restoration rate under NT. A specific emphasis was given to the largest macroaggregate size class (8–19mm) because of its importance to protecting the recently deposited labile SOC. A discriminant analysis of principal components (DAPC) indicated that NV soil is modified by conversion to an arable land use and that, mechanical tillage, biomass input, and their interactions drastically influence the distribution of aggregate-size classes, aggregation indices, and SOC distribution within aggregates. At both sites, soil aggregation indices were positively impacted by NT and associated with SOC concentration in the labile fractions (e.g., total polysaccharides (TPS), hot water extractable organic C (HWEOC), particulate organic C (POC)). At the PG site, the 8–19mm aggregate size fraction was significantly affected by land use and tillage treatments and represented 54%, 43%, and 72%, under NV, CT, and NT in 0–20cm depth, respectively. Furthermore, the 8–19mm size fraction stored 55%, 45%, and 71% of the total SOC stock under NV (53.8MgCha−1), CT (28.5MgCha−1) and NT (51.2MgCha−1), respectively. At the LRV site, the 8–19mm aggregate size fraction decreased from 50% under Cerrado NV to 35% under CT, and ranged from 33% to 51% under diverse biomass-C input under NT in 0–20cm depth. The 8–19mm size fraction stored 52%, 37%, and 41% of the total SOC stock across all aggregate sizes under NV (25.4MgCha−1), CT (11.7MgCha−1), and NT (9.9–18.1MgCha−1), respectively. The difference in SOC stock among land uses is largely attributed to storage in the 8–19mm aggregate size class, indicating that NT cropping systems rebuilt the largest macroaggregates, which are crucial for stabilization of SOC.