Tillage and growth of a wheat crop in a loamy sand

1982 ◽  
Vol 33 (6) ◽  
pp. 887 ◽  
Author(s):  
AP Hamblin ◽  
D Tennant ◽  
H Cochrane

In the fourth consecutive year of a long-term tillage trial in a loamy sand in Western Australia above- and below-ground growth of a wheat crop (cv. Gamenya) was monitored. The grain yield was nearly 20% greater in the crop sown after ploughing than in those crops sown by direct drilling. A similar trend had been noted in each preceding year. Cumulative water use was 15 and 9 mm less with zero and minimum tillage than with ploughing. The ploughed treatment had lower soil strengths, not only in the seedbed but also to 50 cm in the subsoil, until 8 weeks after seeding. These lower soil strengths coincided with more-rapid wetting of the subsoil under ploughing, and faster root extension rates. Dry matter production was significantly greater in the ploughed crop from the initial sampling date, and direct-drilled crops were not able to compensate in the later part of the season, despite using slightly more water during that period. The slower wetting of the profile under direct drilling was a persistent feature over several seasons in this soil type. It was considered responsible for the increased soil strength and slower root extension rates. The implications of direct-drilled sandy soils for crop productivity, and drainage control of recharge soils in saline catchments, are discussed.

2016 ◽  
Vol 51 (9) ◽  
pp. 1633-1642 ◽  
Author(s):  
Claudio Hideo Martins da Costa ◽  
Carlos Alexandre Costa Crusciol ◽  
Jayme Ferrari Neto ◽  
Gustavo Spadotti Amaral Castro

Abstract The objective of this work was to evaluate the long-term effects of the surface application of lime on soil fertility and on the mineral nutrition and grain yield of soybean, and of black oat and sorghum in crop succession. The experiment was carried out on a clayey Oxisol, in a randomized complete block design, with four replicates. Treatments consisted of lime the rates of 0, 1,000, 2,000, and 4,000 kg ha-1, applied in October 2002 and November 2004. Soil samples were collected at five soil layers, down to 0.60-m depth. Surface liming was effective in reducing soil acidity and increasing Ca2+ and Mg2+ contents in the subsurface. Moreover, it increased available phosphorus contents and soil organic matter in the long term (48 to 60 months after the last lime application). Surface liming improved plant nutrition, mainly for N, Ca, and Mg, and increased dry matter production and grain yield of the crops, even in years with regular distribution of rainfall. The greatest productivities of soybean, black oat, and sorghum were obtained with the respective estimated lime doses of 4,000, 2,333, and 3,281 kg ha-1, for shoot dry matter, and of 2,550, 3,555, and over 4,000 kg ha-1, for grain yield.


2004 ◽  
Vol 142 (2) ◽  
pp. 141-151 ◽  
Author(s):  
J. ERIKSEN ◽  
F. P. VINTHER ◽  
K. SØEGAARD

Grass-legume associations may offer a way of improving the N efficiency of dairy farming, but may also have an adverse impact on the environment by increasing leaching losses. Nitrate leaching from four cropping sequences with different grassland frequency and management (long-term grazed, long-term cut, cereals followed by 1 and 2-year grazed leys) were investigated on a loamy sand in central Jutland for both unfertilized grass-clover (perennial ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.)) and fertilized perennial ryegrass (300 kg N/ha) swards during 1997–2002. Furthermore, 1 year (2001) of N2 fixation in 1-, 2- and 8-year-old grass-clover pastures was determined. Nitrate leaching from grazed unfertilized grass-clover was always considerably lower than from grazed fertilized ryegrass. The effect of grassland age on nitrate leaching was insignificant in grass-clover but clear in grazed ryegrass, where levels increased dramatically with sward age. In production years 6–8, leaching from grass-clover was only 9–13% of the comparable losses from ryegrass. Under the cutting regime grass-clover showed a significant reduction in both yield and N-removal with increasing sward age, whereas for ryegrass these figures did not show any decreasing trend. N2 fixation was lower in 8-year-old swards compared with fully established 2-year-old swards as a consequence of lower dry matter production, lower clover content and a lower proportion of clover-N derived from the atmosphere. The results from the present study indicate that the higher leaching losses observed in fertilized grass compared with unfertilized grass-clover systems were caused by (1) a reduction in N2-fixation in grass-clover over time and (2) a reduction in dry matter production in grass-clover over time, lowering the grazing intensity and the recycling of grassland N via animal excreta.


1989 ◽  
Vol 40 (5) ◽  
pp. 421 ◽  
Author(s):  
P.J. Hocking

A study was made of the seasonal changes in dry matter production and patterns of nutrient accumulation by Phragmites australis in a nutrient-enriched swamp in inland Australia. The density of live shoots was highest (224 m-2) in October, but the peak standing crop of live shoots (9890 g m-2) occurred in early May. Peak below-ground biomass (21 058 g m-2) occurred in early August. Rhizome biomass constituted 75% of the below-ground biomass, and showed a distinct seasonal pattern. Net annual above-ground primary production (NAAP), estimated by the maximum-minimum method, was 9513 g m-2. Correction for shoot mortality and leaf shedding before, and production after, the maximum standing crop was attained increased NAAP to 12 898 g m-2. Whole plant production estimated by the maximum-minimum method was 9960 g m-2, and the corrected estimate was 14 945 g m-2. A model of dry-matter production indicated that translocation of carbohydrate from rhizomes could have provided 33% of the dry matter of shoots. About 23% of the dry matter of shoots was redistributed to below-ground organs during senescence. Concentrations of N, P, K, S, Cl and Cu declined, but concentrations of Ca, Mg, Na, Fe and Mn increased as shoots aged. Concentrations of N, P and Zn in rhizomes reached maxima in winter, and decreased in spring. Rhizomes usually contained the greatest quantity of a nutrient in the whole plant, and roots usually had less than 25% of the total plant content. There were seasonal fluctuations in the quantities of N, P, K, Zn and Cu in rhizomes. Nutrient accumulation by live shoots was underestimated by 22-55% using the maximum-minimum method. Nutrient budgets showed considerable internal cycling of N, P, K, S and Cu from rhizomes to developing shoots in spring, and from senescing shoots to rhizomes during autumn and winter.


1984 ◽  
Vol 102 (2) ◽  
pp. 371-382 ◽  
Author(s):  
A. H. Weir ◽  
P. L. Bragg ◽  
J. R. Porter ◽  
J. H. Rayner

SummaryA whole crop computer simulation model of winter wheat has been written in FORTRAN and used to simulate the growth of September- and October-sown crops of Hustler wheat at Rothamsted for the years 1978–9, 1979–80 and 1980–1. Results of the simulations, which are for crops with adequate water and nutrients, are compared with observations from experiments at Rothamsted. The model uses daily maximum and minimum temperatures and daylength to calculate the dates of emergence, double ridge, anthesis and maturity of the crops and the growth and senescence of tillers and leaves. In the simulations, the canopy intercepts daily radiation and produces dry matter that is partitioned between roots, shoots, leaves, ears and grain. Partial simulations, using observed LAI values, produced dry matter in close agreement with observations of late-sown crops, but consistently overestimated the total dry-matter production of the early-sown crops. Full simulation described satisfactorily the average difference in dry-matter production to be expected with changes in time of sowing, but did not give as close correspondence for individual crops. A grain growth submodel, that linked maximum grain weight to average temperatures during the grain growth period, correctly simulated the observed growth of individual grains in the 1981 crop. The benefits to be obtained by combining whole crop modelling with detailed crop observations are discussed.


1981 ◽  
Vol 11 (3) ◽  
pp. 599-605 ◽  
Author(s):  
Michael R. Keyes ◽  
Charles C. Grier

Above- and below-ground net primary production was estimated for 40-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stands growing on sites with apparently large differences in productivity potential. Aboveground net production was estimated from direct measurements of tree growth; belowground productivity was derived from data obtained by sorting live and dead roots from soil cores used in combination with measurements of root growth on observation windows.Aboveground net production was 13.7 t•ha−1 on the high productivity site and 7.3 t•ha−1 on the low productivity site. Belowground dry matter production on the high productivity site was 4.1 t•ha−1 compared with 8.1 t•ha−1 for the poorer site. On the more productive site, 8% of total stand dry matter production was in fine roots in contrast to over 36% on the poorer site. The difference in total net production (aboveground plus belowground) between the two sites was small (2.4 t•ha−1). Apparent differences in aboveground productivity may, to a large extent, result from the need for a greater investment in the fine roots on harsher sites.


Weed Science ◽  
1981 ◽  
Vol 29 (5) ◽  
pp. 521-524 ◽  
Author(s):  
O. P. Kataria ◽  
Vijay Kumar

Control of littleseed canarygrass (Phalaris minor Retz.), wild oat (Avena fatua L.), common lambsquarters (Chenopodium album L.), and field bindweed (Convolvulus arvensis L.) in dwarf wheat (Triticum aestivum L.) fields was studied with five herbicides and hand weeding. Terbutryn [2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine] and 1-benzthiazol-2-yl-1,3-dimethylurea controlled the weeds more effectively than did two hand weedings. Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], nitrofen (2,4-dichlorophenyl p-nitrophenyl ether), and dichlormate (3,4-dichlorobenzyl methylcarbamate), proved only partially effective against weeds, and were therefore significantly inferior to two hand weedings. Spikes per meter of row length and test weight of wheat were increased significantly by 1-benzthiazol-2-yl-1,3-dimethylurea (1.5 to 2 kg/ha), terbutryn (0.5 kg/ha), and two hand weedings over the yields of the weedy check. The 1-benzthiazol-2-yl-1,3-dimethylurea showed a high degree of selectivity in the wheat crop at 2 kg/ha and increased yields to those of weed-free plots. Terbutryn was almost as effective as 1-benzthiazol-2-yl-1,3-dimethylurea, which increased the wheat yields over those of the weedy check by 19.8 and 42.4% during the 1974/75 and 1975/76 seasons, respectively. Tolerance of dwarf wheat to terbutryn at 0.75 kg/ha was variable, resulting in significant decreases in yield components and grain yield. Dry-matter yield of wheat was negatively correlated with the dry matter production of weeds.


2014 ◽  
Vol 63 (1) ◽  
pp. 149-158
Author(s):  
Imre Vágó ◽  
M. Sipos ◽  
L. Tolner ◽  
B. Eichler-Löbermann ◽  
I. Czinkota

The effects of genotypes, nutrient and water supply on the dry matter production and potassium uptake dynamics of maize (Zea mays L.) were studied on chernozem soil in the Debrecen-Látókép long-term field experiment (Eastern Hungary).According to the experimental results and calculations it can be concluded that — in addition to the previously used and considered soil and plant nutrient contents — the calculation of the plant-extracted nutrient amount (depending on the applied hybrid, NPK nutrient levels and water supply) is suggested to enable the characterization of the growth and nutrient demand dynamics of maize genotypes. This parameter gives information not only about the available nutrient amount at a given sampling time, but about the supply level of plants up to the sampling time as well. For the proper characterization of the mentioned dynamics of maize plants authors suggest to take the following sampling times into consideration: the intensive vegetative growth period, the switch between the vegetative and generative growth phases (silking), and the grain filling phase.


2015 ◽  
Vol 154 (6) ◽  
pp. 1090-1101 ◽  
Author(s):  
A. M. RATJEN ◽  
H. KAGE

SUMMARYThree different explanatory indicators for reduced light use efficiency (LUE) under limited nitrogen (N) supply were evaluated. The indicators can be used to adapt dry matter production of crop simulators to N-limited growth conditions. The first indicator, nitrogen factor (NFAC), originates from the CERES-Wheat model and calculates the critical N concentration of the shoot as a function of phenological development. The second indicator, N nutrition index (NNI), calculates a critical N concentration as a function of shoot dry matter. The third indicator, specific leaf nitrogen (SLN) index (SLNI), has been newly developed. It compares the actual SLN with the maximum SLN (SLNmax). The latter is calculated as a function of the green area index (GAI). The comparison was based on growth curves and fitted to empirical data, and was carried out independently from a dynamic crop model. The data set included four growing seasons (2004–2006, 2012) in Northern Germany and seven modern bread wheat cultivars with varying N fertilization levels (0–320 kg N/ha). The influence of N shortage on LUE was evaluated from the beginning of stem elongation until flowering. With the exception of 2005, the highest productivity was observed for the highest N level. A moderate N shortage primarily reduced GAI and therefore light interception, while LUE remained stable under moderate N shortage. The relative LUE (rLUE) of a specific day was defined as the ratio of actual to maximal LUE. None of the indicators was proportional to rLUE, but the relationships were described well by quadratic plateau curves. The correlation between simulated and measured rLUE was significant for all explanatory indicators, but different in terms of mean absolute error and coefficient of determination (R2). The performance of SLNI and NNI was similar, but the goodness of prediction was much lower for NFAC. Compared with NNI and NFAC, SLNI corresponded to leaf N and was therefore sensitive to N translocation from leaves to growing grains during the reproductive stage. For this reason, SLNI may have the potential to improve simulation of dry matter production in wheat crop simulators.


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