Crop Rotation Treatments Research Articles

Assessment of Two Chemical Extraction Methods as Indices of Available Nitrogen

AbstractA soil test for estimating mineralizable N in soil is needed to improve fertilizer use efficiency. Our objectives were to: (i) test the effectiveness of two chemical indices in estimating potentially mineralizable N (N0) in soils, and (ii) determine if these indices could be used to differentiate the impact of cultural practices on the N‐supplying capacity of soils. We collected samples from the 0‐ to 0.15‐m depth of 42 soils representing all agroecological regions in Saskatchewan, Canada. We determined (i) N mineralized (Nmin), N0, and the rate constant (k) by aerobic incubation at 35°C for 24 wk, and (ii) the NH4‐N extracted by (a) 2 M KCl heated at 100°C for 4 h, and (b) a steam‐distilled phosphate‐borate solution buffered at pH 11.2. The association between N0 and the hot 2 M KCl extracted NH4‐N was close (r2 = 0.78, significant at P < 0.001); the relationship between N0 and the phosphate‐borate NH4‐N was slightly less precise (r2 = 0.73, P < 0.001). When NH4‐N extracted with cold 2 M KCl was subtracted from the NH4‐N extracted with hot extractants, the association with Nmin was weaker (r2 ≤ 0.50). The value of k for the 42 soils was generally constant (avg. 0.067 ± Sxt 0.05 = 0.040 wk−1). In a second experiment, we compared the two chemical extractants vs. the N mineralized in a 24‐wk incubation regarding their effectiveness in differentiating the effects of eight 37‐yr crop rotation treatments on N‐supplying capacity. These three indices performed effectively in this regard. For example, the 2 M KCl NH4‐N was closely associated with N mineralized in 24 wk (r2 = 0.92), as was phosphate‐borate NH4‐N (r2 = 0.88; both significant at P < 0.001). We concluded that the chemical extractants may provide a quick test for assessing N‐supplying capacity of the soil.

Influence of crop rotation, manure and fertilizers on bread making quality of wheat (Triticum aestivum L.)

The effects on bread-making quality of crop rotation, fertilizers and manure treatments were evaluated in a long term experiment in which the combinations of organic manure, mineral nitrogen, phosphorus and potassium fertilizers were applied to three crop rotations for a total of 33 different treatments. Protein concentration evaluated for 12 years varied from 10.0 per cent to 12.8 per cent with years and from 10.70 per cent to 13.21 per cent among treatments.The highest grain yields were obtained in the two-year (wheat-maize) or nine-year (wheat-maizelucerne) rotations, coupled with a great variability for quality, as evaluated with the Chopin alveograph. Potassium fertilizer did not affect yield or quality, while positive effects of phosphorus were evident only after continuous cropping with wheat.When wheat was grown continuously, the application of nitrogen fertilizer gave grain of optimum quality but, even in combination with the highest rate of manure, did not raise the yield to the levels achieved by the 2 or 9 year rotations. In the wheat-maize rotation, maximum yield and quality was achieved with the highest rate of fertilizers even in the absence of manure. In the rotation that included lucerne, maximum yield was obtained with the lowest rate of fertilizers but, to optimize the quality, it appeared necessary to apply the highest rate of nitrogen (200 kg N ha−1).

Perennial Weed Populations After 14 Years of Variable Tillage and Cropping Practices

Management of perennial weeds is a major concern in reduced-tillage cropping systems. Field research was conducted at Nashua, IA, from 1977 through 1990 to evaluate the long-term impacts of tillage and cropping patterns on perennial weed populations in corn and soybean production. Continuous corn and a corn/soybean rotation were conducted utilizing moldboard plow, chisel plow, ridge tillage, and no-tillage systems. The research area was free of established perennial weed species at the initiation of the experiment in 1977. Hemp dogbane was observed by 1980, with the greatest densities in no-tillage. By 1990, continuous corn had greater hemp dogbane densities with no-tillage than other tillage system by crop rotation treatments. American germander densities were not affected by tillage systems in 1980 and 1981, but by 1990, corn/soybean rotations had greater densities in moldboard plow than other tillage systems. Field bindweed developed primarily in the corn/soybean rotations with the greatest densities occurring in no-tillage. Greater and more diverse populations of perennial weeds developed in reduced-tillage systems than in the moldboard plow system. However, practices used to control annual weeds and environmental factors interacted with tillage to regulate perennial weed populations.

Tillage and Crop Rotation Effects on Soil Organic Matter in a Typic Hapludult of Northern Alabama

A study was conducted to determine the impact of long-term (1980-1990) tillage and crop rotation treatments on soil organic C and N concentrations in a Typic Hapludult at Crossville, Alabama. Tillage treatments included conventional tillage (CT) and no-till (NT), and crop rotation treatments were continuous soybean (Glycine max L.)-wheat (Triticum aestivum L.) cover (SW), continuous corn (Zea mays L.)-wheat cover (CW) and corn-wheat cover-soybean- wheat cover (CWSW). Surface soils (0 to 5, 5 to 10, and 10-20 cm depth increments) were sampled on 31 October 1990 and analyzed for organic C and N. After 10 years, soil organic C and N concentrations and degree of stratification were greater under NT than CT due to differential placement of crop residues in relation to the soil surface. Highest levels of soil organic C and N were found under CW and CWSW rotations in combination with NT due to greater amounts of crop residues added over the 10 year cropping period.

The effect of crop rotation and chemical soil treatment on the growth of raspberry(Rubus idaeus)in soils with replant problems

A pot experiment indicated that in a soil with a replant problem some raspberry cultivars (e.g. Glen Moy and Glen Clova) grew better and showed smaller growth responses to a fungicide (benomyl) and a nematicide (aldicarb) treatment than others (e.g. ‘Mailing Promise’ and ‘Mailing Jewel’). However, although untreated ‘Glen Moy’ grew slightly larger in a field trial than untreated ‘Glen Clova’ and ‘Mailing Jewel’, all three cultivars showed similar large increases in cane growth in plots treated with dazomet. A crop rotation in which raspberry followed a three-year break of cereals, strawberry or fallow did not improve the growth of the replanted raspberry compared with raspberry following raspberry. Nor was the increased growth response to replanting treatments with either full or half rates of dazomet influenced by crop history. Populations of Pratylenchus penetrans were low after planting treatments (< ten 200“1 soil), and, from the lack of a growth response to aldicarb treatments, they appeared to be causing little or no damage in either field trial. Also, there was little growth response to an additional nitrogen treatment. Hence, the main part of the dazomet effect is attributed to control of unknown soil- borne fungi. Pot tests indicated that the beneficial effects of dazomet treatment persisted only for one or two years.

Detachment of Soil as Affected by Fertility Management and Crop Rotations

AbstractAn experiment was initiated on Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) in 1981 to compare the effects of fertility management and crop practices on splash detachment of soil. Experimental treatments included comparisons of crop rotations of soybean [Glycine max (L.) Merr.] after corn (Zea mays L.) (SB), corn after soybean (C), and oat/red and yellow sweetclover (Avena sativa L./Trifolium pratense L. and Mellilotus officinalis Lam.) after corn (O/CL). For each crop rotation, there were two management options, either added manure (OR) or herbicide plus chemical fertilizer (HF). The seventh treatment was continuous corn (CC) with herbicide, chemical fertilizer, and insecticide. Soil surface samples from each treatment were subjected to rainfall intensities of low (35 mm h−1), medium (62 mm h−1), and high (120 mm h−1). Total splash detachment of soil from simulated rainfall was linearly related to rainfall intensity. For all crop rotation treatments, total splash detachment generally was greater for manured soils than from soil with herbicides and fertilizer. Continuous corn had the lowest soil splash detachment at low intensity, second highest splash detachment at medium intensity, and the highest splash detachment at high intensity. This trend clearly indicated that rate of splash detachment of CC was higher than from soil under crop rotations. The splash detachment rates were 48, 40, 39, and 31 mg cm−3 for CC, C, SB, and O/CL, respectively. Treatment by rainfall intensity interaction was significant, which suggested that intensity and crop rotation were not independent in their effect on soil splash detachment. Soil aggregation as inferred from geometric mean diameter (GMD) indicated that CC had the lowest degree of aggregation (150) as compared to 211 for C, 225 for SB, and 313 for O/CL.

EFFECT OF CROPPING, SUMMERFALLOW AND FERTILIZER NITROGEN ON NITRATE-NITROGEN LOST BY LEACHING ON A BROWN CHERNOZEMIC LOAM

In 1982, six crop rotation treatments that were initiated in 1967 on a Orthic Brown Chernozemic loam were sampled for soil NO3-N and moisture to a depth of 240 cm. Soil samples were taken on 18 May and 10 June from all treatments, on 2 Sept. on fallow treatments only, and on 14 Oct. from cropped treatments. Precipitation during the sampling period was about 23% above the long-term average. It was estimated that at least 123 kg NO3-N∙ha−1 were leached from the top 240 cm of fallow soils. Leaching appeared to result from a portion of the precipitation moving through macro soil pores. There was evidence that water and NO3-N might also move upwards from below the 240-cm depth. Of the six rotations examined, the 2-yr and 3-yr spring wheat (Triticum aestivum L.) rotations lost the most NO3-N. The presence of fall rye (Secale cereale L.) in a fallow-rye-wheat rotation was very effective in reducing NO3-N losses. Spring wheat, when grown continuously, was also very effective in reducing NO3-N losses but even here there was some evidence of leaching beyond the root zone. Application of fertilizer N and P at amounts based on soil test recommendations reduced NO3-N leached. It was estimated from long-term precipitation data, that over the past 100 yr about 20% of the soil organic N that was present at the time of breaking the land has been lost from the soil via leaching. It was concluded that leaching losses of N from the soils on the Canadian prairies had been greatly underestimated and were partly responsible for losses attributed to the more visible wind erosion. Key words: Nitrate movement, crop rotations, fertilizer and leaching, summerfallow and leaching, bimodal leaching

Control ofSeptoria nodorumon Wheat with Crop Rotation and Seed Treatment

Control of<i>Septoria nodorum</i>on Wheat with Crop Rotation and Seed Treatment

Nutrient Content of Sorghum Leaves and Grain as Influenced by Long‐Term Crop Rotation and Fertilizer Treatment1

AbstractThe objective of this research was delineation of longterm crop rotation and fertilizer influence on levels of N, P, K, Ca, and Mg in sorghum leaves and grain. Continuous farming practices may introduce gradual departures in the prevailing initial biological, chemical, and physical characteristics of the plant root environment, thereby altering soil productivity characteristics. These chnges, as they alter nutrient composition and yield of crops, can be documented from long‐term field experiments maintained under continuous farming and fertilization programs. The treatments featured continuous versus rotations of grain sorghum (Sorghum vulgare), wheat (Triticum aestivum) and cotton (Gossypium hirsutum) with and without fertilizer. Most treatments have been applied annually for over 20 years. Fertilization of grain sorghum predominantly consisted of N and P at rates of 45 and 20 kg/ha, respectively, in field plots on a Houston Black clay soil (fine montmorillonitic thermic family of Udic Pellusterts).Apart from some selective positive influence on sorghum leaf N, leaf P and leaf K, the crop rotational effect on leaf composition was considered inconclusive. Generally, crop rotation did result in larger grain production with fertilized as well as with unfertilized sorghum.Levels of sorghum leaf N, leaf P, leaf K, and leaf Ca were mostly higher in plants receiving fertilizer than in checks. Grain sorghum leaf N, leaf P, leaf Ca, and leaf Mg percentages decreased, increased, or remained nearly constant during the interval from plant booting to half bloom. Sorghum leaf K percentages generally decreased from booting to half bloom. Fertilizer increased grain protein percentage and grain yield. Yet, high rates of fertilizer are not usually recommended in the Texas Blackland Prairie because of frequent soil moisture depletion prior to or at grain formation.Sorghum leaf composition, grain protein level and grain yield portrayed noticeable response to applied cattle manure plus fertilizer N and P. As the measurable response to fertilizer P was below expectation, its significance on longterm maintenance of balanced soil fertility remains an important consideration.

Effect of Crop Rotation and Fertilizer Treatment on the Nitrogen and Organic Carbon Contents of a Prairie Soil

AbstractThe effects of cropping systems and soil treatments on the nitrogen and organic carbon contents of Geary silt loam were studied in 1915, 1923, 1934, 1946, and in 1956 on the Agronomy Farm at Manhattan, Kansas.Losses of nitrogen and organic carbon were largest where the original contents of these constituents were highest. Losses were most rapid in the earlier years of the study. Largest losses occurred under a 3‐year rotation of corn, soybeans (for hay), wheat. Losses tended to be lower in the continuous wheat plots than in plots under rotations including row crops and legumes in addition to wheat.Differences between losses of nitrogen and organic carbon under the different fertility treatments were small. However, losses were greatest under phosphate, and phosphate and potash treatments, and were smallest under the complete fertilizer treatment.Although alfalfa increased the nitrogen content of the subsoil slightly, the other crops in the rotation reduced it so that the rotation studied did not appreciably change the subsoil nitrogen content.