Crop Growth Status Research Articles

Sugarbeet Response to Subsoiling and Wheel Traffic

AbstractNormal tillage practices often create poor physical conditions for crop growth on lake plain soils in Michigan. Tillage studies were conducted in 1983 on Parkhill loam (fine‐loamy, mixed, nonacidic, mesic Mollic Haplaquept) and from 1983 to 1985 on Charity clay (fine, illitic (calcareous), mesic Aerie Haplaquept) to evaluate the potential for increasing sugarbeet (Beta vulgaris L.) yield by reducing the physical limitations of these soils. Treatments consisted of eight combinations of a primary tillage and secondary tillage variable. Primary tillage was applied in the fall and consisted of subsoiling and moldboard plowing (SMP), subsoiling and shallow chiseling (SCH), moldboard plowing (MP), or shallow chiseling (CH). The secondary tillage vairable consisted of the presence or absence of tractor wheel traffic occurring during seedbed preparation. Response of sugarbeet ‘US‐H20’ and ‘US‐H23’ was evident each year and was attributed in part to improved soil aeration where subsoiling was performed and where wheel traffic was absent. Response was greatest in 1983 when subsoiling increased root yield of US‐H20 by 10.7 Mg ha−1 on Parkhill loam and by 7.6 Mg ha−1 on Charity clay. Elimination of preplant wheel traffic increased root yields by an average of 8.3 Mg ha−1 on Charity clay that year. Recoverable sucrose yield was affected in proportion to root yield each year because tillage had no effect on recoverable sucrose concentration. The need to minimize wheel traffic in sugarbeet production systems, regardless of the primary tillage practices employed, was evidenced by results of this study.

Physical Conditions of a Lake Plain Soil as Affected by Deep Tillage and Wheel Traffic

AbstractNormal fall and spring tillage practices create poor physical conditions for crop growth on lake plain soils in Michigan. Charity clay [fine, illitic (calcareous), mesic Aeric Haplaquept] (Mahjoory and Whiteside, 1976) is an example of such a soil. It has poor internal drainage due to its naturally dense subsoil and is susceptible to physical degradation because of its unstable surface. Tillage studies were conducted from 1983 to 1985 to evaluate the potential for reducing the physical limitations of Charity clay. Treatments consisted of four combinations of a primary and secondary tillage variable. The primary tillage variable involved the application or omission of deep tillage using a triple‐shanked subsoiler prior to moldboard plowing. The secondary tillage variable involved the presence or absence of tractor wheel traffic prior to planting. Subsoiling improved the physical conditions of Charity clay below the Ap horizon. Soil bulk density (ρb) was reduced by 0.05 Mg m−3, and pore size distribution (PSD) was altered such that the volume of pores with radii larger than 150 µm was doubled. Preplant wheel traffic caused subsoil compaction, increasing ρb by about 0.06 Mg m−3, and altered all indicators of soil compaction in the Ap horizon, especially PSD and saturated hydraulic conductivity. The need to minimize wheel traffic regardless of the primary tillage practices employed was evidenced by the results of this study.

A single decision‐maker approach to irrigation reservoir and farm management decision making

A model for optimizing short‐, intermediate‐, and long‐run irrigation decisions for surface water reservoirs is developed for a river valley irrigation system controlled by one decision maker. The modeled valley is characterized by highly variable reservoir inflows and crop growing conditions, and irrigable land supplies which are plentiful relative to available water. It advances similar work of the early 1970s pertaining to a corn monoculture by using a complex soil water‐plant growth simulation model for cotton developed by crop scientists over a number of years, and by employing an extra simulation model to simulate the effects of using optimal decisions derived by dynamic programming. The results indicate a potential for disagreement about reservoir management strategies and level of irrigation development between irrigators, other members of the local economy, and national economy policy makers. The assumption of one decision maker internalizes the derivation and communication of supply and demand probabilities, giving the results a level of economic efficiency which makes them a standard against which to judge the results of decentralized models.

高精度追肥作業技術の開発 ＩＩ 春・秋作ハクサイへの適用と追肥量の限界

1) The effect of the side-dressing application toward the crop growth and yield was discussed when side-dressing to direct sown chinese cabbage was applied by accurately controlling amount of fertilizer distribution according to the individual crop growth condition at the course of growth.2) In case of spring-sown cropping, the more difference among the applied amount of fertilizer distribution there was, the less difference among the yield (total fresh crop weight and eatable fresh crop weight) there was when giving the larger canopy crop less fertilizer and the smaller canopy crop much fertilizer. The uniform product possibility would be able to resulted by the fertilizer correction treatment. However, the existance of limitation that the yield difference among the each crop fertilizer distribution was estimated.3) In automn-sown cropping, the effect of side-dressing to the crop growth was not clear on the stage of 20 days passed after fertilizer application. Moreover, the response of the total fresh crop weight at the harvest time is quicker than that of the eatable fresh crop weight in case of spring-sown cropping. It will be effective for increasing the crop yield to apply the immediate response fertilizer at the course of growth.4) New model substituted by a cubic expression is proposed to express fertilizing function of fertilizer correction treatment.

Winter wheat vegetation indices calculated from combinations of seven spectral bands

Spectral reflectance data were obtained for winter wheat over a full growing season. Four irrigation treatments, applied to six genotypes, provided a variety of crop growth conditions. Leaf area index, green ground cover, total wet and total dry phytomass, and leaf phytomass measurements were taken monthly during the winter and biweekly during the spring. Reflectance measurements were made with a radiometer having three visible, two near-IR and two mid-IR bands. Vegetation indices, calculated from various band combinations, were linearly related to the five plant parameters. Of the 1240 vegetation indices formed, ratio indices had the higher (0.79–0.86) coefficients of determination ( r 2) than N-space greenness (0.61–0.81) when related to the plant parameters. The commonly used IR/red ratio produced considerably lower r 2 values than many of the other ratio indices. The mid-IR bands appeared more frequently in the ratio indices than in the greenness indices. The results show the relative merits of the seven bands, when combined into vegetation indices, to estimate various plant parameters.

A Design and Methods of Analysis to Monitor Crop Growth Conditions Illustrated with Sorghum Screening Trails for Resistance toStriga

SUMMARYChecker-board field layouts are used to screen sorghum genotypes for resistance toStriga. A systematic check entry is used to monitor crop growth conditions and methods to analyse the results are assessed.

Effects of soil management practice on soil physical conditions affecting root growth

Cultivation and drainage are two major management techniques used to modify soil physical conditions for crop growth. In England and Europe ploughing increased the volume of macropores (pores of diameter >50 μm) but markedly reduced their continuity between topsoil and subsoil compared with direct drilling using a triple disc drill. In Australia, during the first year after pasture, tine cultivation to 100 mm had no greater adverse effect on pore continuity than had direct drilling using a tine drill. The importance of macropores for effective land drainage was evident from the reduced efficiency of mole channels in the presence of a cultivation pan. Root growth and activity were related to the volume of macropores but were impaired when the continuity of those pores was reduced or, as in undrained land, they became water-filled.

An analysis of climatic environments for plant-breeding purposes

Variations in the regional means of a number of growing-season climatic variables, and combinations of them, are not highly correlated with the long-term regional distribution of mean wheat yields in Western Australia or with their variation between years. The data suggest that the growing season is characterized by a cyclical alternation of favourable and unfavourable conditions for crop growth. This oscillating pattern varies in amplitude and wavelength as a result of unpredictable 'between'- and 'within'-season variation in the regional distribution of rainfall. In the central zone of the study area, wheat production is subject mainly to between-season variation whilst in more marginal areas yield variation is confounded by opposing and reciprocating within-season effects. The consequences for plant breeding are that specific regional environments expected on the basis of climate do not occur predictably in the short term. It is argued that breeding objectives, selection strategies and regional testing should initially avoid complications associated with specific marginal environments by concentrating on general adaptability within the central zone, which monitors between-season variation only. Subsequent evaluation for additional adaptive features specific to marginal areas should be undertaken.

Irrigation Development Planning: Aspects of Pakistan Experience by I. D. Carruthers. Department of Economics, Wye College (University of London), Ashford, Kent, December 1968.

In this little book, the second in a series of Agrarian Development Studies, issued by the Economics Department of Wye College, the author draws upon four years' experience with the consultants to the Water and Power Development Authority in West Pakistan to review the main technical and economic factors to be considered in planning irrigation development. The first chapter describes, in general terms, some of the basic relation¬ships between crop growth and water and drainage conditions. The author warns that in arid areas water tends to be regarded as a unique resource. Assigning supreme priorities to single resources can be very damaging to economic development since mere technical feasibility is regarded as justifying irrigation projects, regardless of whether they are economically justified.

Cultivation of Unirrigated Cambodia Cotton in Madras State

Out of the total area of about 5,29,900 acres under Madras Americans in the state during 1956-57, the rainfed Cambodia accounted for 2,51,500 acres. Cambodia cotton is cultivated under rainfed conditions mostly in the districts of Coimbatore, Salem, Tiruchirappalli and Madurai where early North East monsoon rains are received. The average yield of the Unirrigated Cambodia raised in the tract is about 40-80 lb. of lint per acre. The success of the rainfed Cambodia crop is mainly dependent on the distribution of rainfall during crop growth and other seasonal conditions. Apart from the weather conditions, which are of course beyond our control, there are ways of getting a good crop adopting suitable cultivation practices which are discussed below.