• Authors:
    • Li, Y. S.
    • Shao, M. A.
    • Zhong, L. P.
  • Source: Agricultural Sciences in China
  • Volume: 4
  • Issue: 1
  • Year: 2005
  • Summary: Based on the experimental data of crop yield, soil water and fertility of a dryland farming ecosystem in northwest China, a systematic analysis is carried out using spring maize and winter wheat to study the dynamics of dryland farming ecosystem productivity and its limiting factors. This paper also discusses which of the two limiting factors, i.e., soil water or fertility, is the primary factor and their dynamics. The result shows that fertility is the primary limiting factor when the productivity is rather low. As chemical fertilizer input increases and the productivity promotes, water gradually becomes the primary limiting factor. Chemical fertilizers and plastic film mulching are the two major driving forces that determine the crop productivity and its stability in these areas.
  • Authors:
    • Sturny, W. G.
    • Ramseier, L.
    • Chervet, A.
    • Tschannen, S.
  • Source: Revue Suisse d'Agriculture
  • Volume: 12
  • Issue: 5
  • Year: 2005
  • Summary: Over the last ten years, conventional plough tillage has been compared to no-tillage on six crop rotation plots in the long-term field trial Oberacker at the Inforama Ruetti in Zollikofen, Switzerland. The deep cambisol of the trial plots contains 15% clay and 3% organic matter. The absence of tillage operations in no-tillage makes a more complex strategy for weed control necessary. Options such as a balanced crop rotation, permanent soil cover, adapted crop residue management and immediate seeding of subsequent crops are used alongside chemical, mechanical, and thermal strategies of weed control. Land use is sustainable in the no-tillage system: No-tilled soil has a higher structural stability and load capacity while being markedly less prone to erosion; less machine usage and traffic reduce (fuel) costs. After seven years of no-tillage, continuous release of soil-borne nitrogen leads to crop yields and qualities at least equal to those obtained with conventional tillage. Two challenges remain only partly solved: (a) the greater dependence on herbicides such as glyphosate and (b) the greater risk of mycotoxin formation in no-tilled winter cereal crops that follow maize. Remedies include adaptations of the crop rotation, chopping of residual maize straw/stalks and cropping of cereal varieties less susceptible to fusarium. In conclusion, no-tillage contributes substantially to maintaining soil fertility on a long-term basis.
  • Authors:
    • Mehuys, G. R.
    • Madramootoo, C. A.
    • Burgess, M. S. E.
    • Mehdi, B. B.
    • Dam, R. F.
    • Callum, I. R.
  • Source: Soil & Tillage Research
  • Volume: 84
  • Issue: 1
  • Year: 2005
  • Summary: Different tillage and residue practices could potentially lead to significant differences in both crop production and soil properties, especially if both practices are implemented over a long time period and on continuous monoculture corn (Zea mays L.). The objective of this research was to determine how differing tillage practices and corn residues affected soil bulk density, corn emergence rates and crop yields over an 11-year period. The experimental site consisted of three tillage practices (no-till, NT; reduced tillage, RT; and conventional tillage, CT) and two residue practices (with grain corn residue, R; without residue (corn crop harvested for silage), NR). Bulk density was 10% higher in NT (1.37 Mg m(-3)) than in CT (1.23 Mg m(-3)), particularly at the 0-0.10 m depth. Spring corn emergence in NTR was slower by 14-63% than all other treatments in 1992-1994. In 1996, corn emergence in the NTR treatment was 18-30% slower, and NTNR was 5-30% faster than all other treatments. No-till with residue (NTR) possibly had the slowest overall emergence due to the higher surface residue cover (8.5 Mg ha(-1) in 1996) and higher bulk density (1.37 Mg m(-3) over the 11 years). Long-term mean dry matter corn yields were not affected by tillage and residue practices during the course of this study; rather climatic-related differences seemed to have a greater influence on the variation in dry matter yields. The long-term cropping of corn under different tillage and residue practices can change bulk density in the surface soil layer, vary the corn emergence without affecting yields, and produce comparable yields between all the tillage and residue practices. (C) 2004 Elsevier B.V. All rights reserved.
  • Authors:
    • Sullivan, D. G.
    • Balkcom, K. S.
    • Lamb, M. C.
    • Rowland, D. L.
    • Faircloth, W. H.
    • Nuti, R. C.
  • Source: Proceedings of the 27th Southern Conservation Tillage Systems Conference, Florence, South Carolina, USA, 27-29 June, 2005
  • Year: 2005
  • Summary: The interaction between reduced irrigation capacity and tillage, including the possible conservation of water with reduced tillage systems, is of vital interest to growers. A field study was initiated in the fall of 2001 to determine crop response under a simulated reduction in irrigation. Three tillage systems were replicated three times each under one of four irrigation levels (100% of a recommended amount, 66%, 33%, and 0% or dryland). Tillage systems were conventional tillage, wide-strip tillage and narrow-strip tillage. The test area was planted in triplicate, in a peanut-cotton-corn rotation, with each crop being present each year. A wheat (cv. AGS 1000) cover crop was drill-seeded each fall on conservation tillage plots. Cover crop termination was performed approximately three weeks prior to planting of each crop species. Tillage was significant for peanut yield and net return at the 0% irrigation level only. No trend in yield was evident, however, net return was consistently high with narrow-strip tillage in all years. Irrigation, at any level greater than 0%, masked tillage effects in both yield and net return. These data confirm the suitability of peanut to conservation tillage practices, including both wide- and narrow-strip tillage.
  • Authors:
    • Zhou, G. Y.
    • Luo, J. J.
    • Stewart, B. A.
    • Yong, W.
    • Fan, T. L.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 106
  • Issue: 4
  • Year: 2005
  • Summary: Wheat ( Triticum aestivum L.) and corn ( Zea mays L.) rotation system is important for food security in the Loess Plateau of China. Grain yield and water-use efficiency (WUE: grain yield per unit of water consumed) trends, and changes in soil properties during a 24-year fertilization experiment in Pingliang, Gansu, China, were recorded. Mean yields of wheat for the 16 years started in 1981 ranged from 1.29 t ha -1 for the unfertilized plots (CK) to 4.71 t ha -1 for the plots that received manure (M) annually with inorganic nitrogen (N) and phosphorus (P) fertilizers (MNP). Corn yields for the 6 years started in 1979 averaged 2.29 and 5.61 t ha -1 in the same treatments. Yields and WUEs declined significantly with lapse of time except CK and MNP for wheat. Wheat yields with the N and M declined at rate of 77 and 81 kg ha -1 year -1, but the decline of 57 kg ha -1 year -1 for NP was similar to that of 61 ha -1 year -1 for straw with N annually and P every second year (SNP). Likewise, the corn yields and WUEs declined from 160 to 250 kg ha -1 year -1 and from 0.01 to 0.03 kg m -3 year -1 among treatments, respectively. These declines were likely to loss of soil fertility and gradual dry weather. Yields were significantly correlated with seasonal evapotranspiration with slopes ranging from 0.5 to 1.27 kg m -3 for wheat and from 1.15 to 2.03 kg m -3 for corn. Soil organic carbon (SOC), total N (TN), and total P (TP) gradually built up with time except the CK, in which TN and TP remained unchanged but SOC and available P (AP) decreased. Soil AP decreased in the N. Soil available K declined rapidly without straw or manure. Balanced fertilization should be encouraged to ensure sustainable productivity in this intensive cropping system. The greatest SOC increases of about 160 mg ha -1 year -1 occurred in the SNP and MNP, suggesting that long-term additions of organic materials to soil could increase soil water-holding capacity which, in return, improves water availability to plants and arrests yield declines, and decrease CO 2 emission from agricultural soils and sustain land productivity.
  • Authors:
    • Barbu, S. A.
    • Gaina, V.
  • Source: Probleme de agrofitotehnie teoretica si aplicata
  • Volume: 27
  • Issue: 1
  • Year: 2005
  • Summary: Aside from the chemical fertilizers applied into soil, foliar fertilizer application with complex solutions containing essential macro- and microelements which contribute to the plant nutrition balance has an important role in increasing crop yield. The paper presents the results obtained in maize and sunflower studies conducted at the ARDI Fundulea (Romania) under dryland conditions during 2001-03, years with special climatic conditions. Some new products, which contribute by supplementing the nutrient needs during vegetation and lead to increases in maize and sunflower yields as well as soil chemical pollution diminution, are tested. The analysis of results, depending on the special climatic conditions of the experimental years, has allowed the elaboration of some important conclusions for agricultural practice. Under the circumstances where no chemical fertilizer has been applied, the foliar fertilizer treatment could represent an important nutrient source for different crops. Both in maize and sunflower, the foliar fertilizers constitute a possibility to increase their yields even in basic fertilizer application.
  • Authors:
    • Pookpakdi, A.
    • Juntakool, S.
    • Suwanketnikom, R.
    • Chinawong, S.
    • Woldetsadik, G.
  • Source: Kasetsart Journal: Natural Science
  • Volume: 39
  • Issue: 1
  • Year: 2005
  • Summary: A field experiment was conducted during the rainy season of 2003 to study the effects of nitrogen rates (0, 10, 20 and 30 kg/ha) and moisture conservation practices (flat bed, ridge furrow, flat bed + mulching and ridge furrow + mulching) on the soil, soil water, yield and yield components of maize ( Zea mays) grown in a rift valley in central Ethiopia. Grain yield was affected by nitrogen fertilizer levels but 1000-grain weight, total biomass, straw yield, soil temperature, soil moisture content, and infiltration rate were not affected by the nitrogen rates. Significant effects in harvest index and water use efficiency of nitrogen rates were observed only at Dera and Melkassa, respectively. Moisture conservation practices improved grain and straw yields, harvest index, and total biomass compared to the use of flat beds due to the availability of moisture. Bulk density, infiltration rate, water use efficiency, and soil moisture content were also affected by moisture conservation practices. Mulching reduced soil temperature prior to maize maturity.
  • Authors:
    • Sayre, K. D.
    • Govaerts, B.
    • Deckers, J.
  • Source: Field Crops Research
  • Volume: 94
  • Issue: 1
  • Year: 2005
  • Summary: Subtropical highlands of the world have been densely populated and intensively cropped. Agricultural sustainability problems resulting from soil erosion and fertility decline have arisen throughout this agro-ecological zone. This article considers practices that would sustain higher and stable yields for wheat and maize in such region. A long-term field experiment under rainfed conditions was started at El Batan, Mexico (2240 m a.s.l.; 19.31 degrees N, 98.50 degrees W;fine, mixed, thermic, Cumulic Haplustoll) in 1991. It included treatments varying in: (1) rotation (continuous maize (Zea mays) or wheat (Triticum aestivum) and the rotation of both); (2) tillage (conventional, zero and permanent beds); (3) crop residue management (full, partial or no retention). Small-scale maize and wheat farmers may expect yield improvements through zero tillage, appropriate rotations and retention of sufficient residues (average maize and wheat yield of 5285 and 5591 kg ha(-1)), compared to the common practices of heavy tillage before seeding, monocropping and crop residue removal (average maize and wheat yield of 3570 and 4414 kg ha(-1)). Leaving residue on the field is critical for zero tillage practices. However, it can take some time-roughly 5 years-before the benefits are evident. After that, zero tillage with residue retention resulted in higher and more stable yields than alternative management. Conventional tillage with or without residue incorporation resulted in intermediate yields. Zero tillage without residue drastically reduced yields, except in the case of continuous wheat which, although not high yielding, still performed better than the other treatments with zero tillage and residue removal. Zero tillage treatments with partial residue removal gave yields equivalent to treatments with full residue retention (average maize and wheat yield of 5868 and 5250 kg ha(-1)). There may be scope to remove part of the residues for fodder and still retain adequate amounts to provide the necessary ground cover. This could make the adoption of zero tillage more acceptable for the small-scale, subsistence farmer whose livelihood strategies include livestock as a key component. Raised-bed cultivation systems allow both dramatic reductions in tillage and opportunities to retain crop residues on the soil surface. Permanent bed treatments combined with rotation and residue retention yielded the same as the zero tillage treatments, with the advantage that more varied weeding and fertilizer application practices are possible. It is important small-scale farmers have access to, and are trained in the use of these technologies. (c) 2004 Elsevier B.V. All rights reserved.
  • Authors:
    • Shea, K. L.
    • Gregory, M. M.
    • Bakko, E. B.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 20
  • Issue: 2
  • Year: 2005
  • Summary: We compared soil characteristics, runoff water quantity and nutrient fluxes, energy use and productivity of three farm types in an unusually dry farming season: conventional (continuous corn and deep tillage), rotation (5-year corn-soybean-oats/ alfalfa-alfalfa-alfalfa rotation with tillage 2/5 years) and no-till (corn-soybean with no cultivation). Soil organic matter content was highest on the rotation farm, followed by the no-till farm, and lowest on the conventional farm. Nitrate content of the soil did not differ significantly among the three farms, although the conventional farm had a much higher input of fertilizer nitrogen. Soil penetrometer resistance was lower and percent soil moisture was higher in the no-till and rotation systems compared to the conventional farm. Soil macroinvertebrate abundance and diversity were highest on the no-till farm, followed by the rotation farm. No invertebrates were found in the soil of the conventional farm. The conventional farm had the highest runoff volume per cm rain and higher nitrogen (N) loss in runoff when compared to the rotation and no-till farms, as well as a higher phosphorus (P) flux in comparison to the no-till farm. These results indicate that perennial close-seeded crops (such as alfalfa) used in crop rotations, as well as plant residue left on the surface of no-till fields, can enhance soil organic content and decrease runoff. The lower soil penetrometer resistance and higher soil moisture on the rotation and no-till farms show that conservation tillage can increase soil aggregation and water infiltration, both of which prevent erosion. Furthermore, crop rotation, and particularly no-till, promote diverse invertebrate populations, which play an important role in maintaining nutrient cycling and soil structure. Crop rotation and no-till agriculture are less fossil-fuel intensive than conventional agriculture, due to decreased use of fertilizers, pesticides and fuel. In this unusually dry year they provided superior corn and soybean yields, most likely due to higher soil moisture as a result of greater water infiltration and retention associated with cover crops (rotation farm) and crop residue (no-till farm).
  • Authors:
    • Ewulo, B. S.
    • Agele, S. O.
    • Oyewusi, I. K.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 72
  • Issue: 2
  • Year: 2005
  • Summary: The interaction of land use and seasonal microclimatic events could explain the differences in soil quality characteristics which mediate biological and physical processes of the soil under low input land use systems (plough plus harrow, strip/heap tillage, manual clearing/no till). It is hypothesised that in a humid tropical Alfisol, low input system involving reduced tillage methods, and mineral fertilizer and/or livestock manure use, would support a higher density of microbial biomass, soil aggregation, organic C and total N and hence improvement in soil quality. The dynamics of biotic and abiotic soil properties as affected by methods of seedbed preparation characterised by manural input and microclimatic transitions from wet to dry season was studied in a maize field in a tropical rain forest Alfisol in Akure, a humid rain forest zone of Nigeria. Each year, trials were carried out during the rainy (April-July) and late (September-December) seasons of 2001 and 2002. Methods of seedbed preparation involving plough plus harrow, strip/heap tillage and no tillage, and addition of different gradients of manures (mineral N and/or plant debris and live stock litter) were imposed on the soil at the site of the experiment (of comparable physical properties of bulk density and texture). Among the treatments, there were significant differences in the values of water holding capacity, aggregate stability (macro-aggregation), concentrations of microbial biomass, organic C, total and mineral N and CEC. In the rainy and late season trials, the strip/heap tillage and the no till treatments improved aggregate stability (as measured by the percent ages of aggregates between 2 and 10 mm of soil) and water holding capacity over plough+harrow. For example, in the rainy season trial, under treatments involving strip/heap tillage and the no till alone and in combination with livestock manuring and residue retention, the values of aggregates between 2 and 10 mm range from (110-116; 113-119 g/kg) and water holding capacity (0.11-0.14; 0.12-0.15 g/g) over plough+harrow (107.3 g/kg; 0.11 g/g). Similar trends were found in the values of soil microbial biomass C (377, 353; 547, 490 g/g dry soil), soil organic C (3.8, 4.3; 5.2, 5.5 g/g) and total N (2.9, 2.3; 2.9, 3.0 mg/g) for strip/heap and no till treatments compared to plough+harrow (327.6 g/g dry soil; 3.4 g/g; 2.8 mg/g). Although the %C microbial to C organic ratio (an indicator of the utilisation of organic carbon by the microbesin terms of organic matter turn over rate) was stable for all treatments, its magnitude was not constant but increased with increases in soil C concentration. The values of microbial biomass carbon to organic carbon (Cmic: Corg) ratio were higher under ploughing and heap tillage combined with mineral N (0.096, 0.099) than in no-till treatment (0.083) in the rainy season trial. Similar trends were obtained in the magnitudes of this parameter in the late season trial. Microbial biomass correlated positively with both soil organic C ( y=0.393 c-6.7; r2=0.99; P< 0.05)