Termite prevalence and crop lodging under conservation agriculture in sub-humid Zimbabwe

Provision of permanent soil cover using crop residues in conservation agriculture (CA) is constrained by livestock grazing and termite consumption in smallholder farming systems of sub Saharan Africa. This study evaluated the effects of surface applied maize (Zea mays L.) crop residues on termite prevalence, crop damage due to termite attack and maize yield over two seasons, 2008/9 and 2009/10. Treatments with residue application rates of 0, 2, 4 and 6 t ha⁻¹ under CA and a conventional mouldboard ploughing (CMP) control were laid out in a randomized complete block design with four replicates on three farm sites in Kadoma, Zimbabwe. Maize residues increased (P < 0.05) termite numbers compared to CMP treatment. Crop lodging at harvest increased (P < 0.05) from 30 to 34% in CMP to 42–48% in CA systems. However, no significant difference was found in crop lodging with increasing residue rates within CA treatments. Significantly higher crop yields were observed under CA (P < 0.05) ranging from 2900 - 3348 kg ha⁻¹ in 2008/9 season compared to CMP with 2117 kg ha⁻¹. Nevertheless, increasing residue cover in CA did not necessarily increase maize crop yield. Thus, increasing crop residue application rates under CA increased termite prevalence while crop lodging was influenced more by soil tillage system than by crop residue application rates.     

Effects of water management and organic fertilization with SRI crop practices on hybrid rice performance and rhizosphere dynamics

A field experiment was conducted to investigate the effects of intermittent versus continuous irrigation, together with different degrees of organic fertilization, on the growth and yield of hybrid rice, looking also at the functioning of the rhizosphere as this is a key element affecting crop performance. The crop management practices employed generally followed the recommendations of the System of Rice Intensification (SRI). The aim of the research was to learn how water management and organic fertilization together would affect crop outcomes. Under intermittent water application as recommended with SRI management (aerobic irrigation, AI), grain yield increased by 10.5–11.3%, compared to standard irrigation practice (continuous flooding, CF). The factor that contributed most to higher yield was increased number of grains per panicle. It was seen that under the range of organic fertilization treatments evaluated, intermittent irrigation compared with CF promoted greater dry matter production and higher leaf area index (LAI) during the main growth stages. Also, the combination of intermittent irrigation and organic material applications significantly increased soil redox potential (Eh), compared with CF, and also the numbers of actinomycetes in the rhizosphere soil. Actinomycetes were evaluated in this study as an indicator of aerobic soil biota. It was seen that with intermittent irrigation, the application of organic material improved the functioning of the rhizosphere and increased yield. However, these results based on 2 years of study reflect relatively short-term effects. The effects of longer-term water management and soil fertilization regimes should be also examined, to know whether these effects continue and, if they do, whether they become greater or less.     

Field crop responses to lime in the mid-north region of South Australia

In the cropping regions of South Australia there is little information on whether acidity and acidification associated with high-input agriculture is affecting crop production and profitability. In much of the mid-north of South Australia, where thermic Calcic Palexeralf soils predominate, the levels of Al are low compared with other acid-soil types reported in comparable studies in Australia. In this study lime requirement curves have been used to predict the lime rate that achieves 80–90% maximum yield for different crop species on 3 sites on the red-brown earth soil type in the mid-north of South Australia. The results given demonstrate that the approach used for predicting lime responsiveness, with lime requirement calculated using the model of [Hochman, Z., Godyn, D.L., Scott, B.J., 1989. The integration of data on lime use by modelling. In: Robson, A.D. (Ed.). Soil Acidity and Plant Growth. Academic Press, Sydney, Australia, pp. 265–301], has provided good estimates of final pH changes. Yield response curves show that the largest yield gains mostly occurred in the second season of the experiment when lime at about 2.0 t/ha increased pH_Ca to 5.5–6.0. With the lime treatments calculated, yield of wheat, barley and faba beans were increased by about 70%, and durum by 30% compared with the control. It would appear that liming to achieve a pH_Ca of 5.2 has removed Al toxicity, and further liming to achieve pH_Ca 5.5–6.0 may have improved other soil properties to realise further yield gains. With cropping in this region commonly using practices that include high fertiliser nitrogen input and retention of crop residues, acidification is likely to be an on-going issue with these red-brown earth soils. Thus it is appropriate that soil testing and, where required, liming at the rate of 1.5 t/ha is used by farmers to both improve cropping profitability and also offset acid input associated with the farming practice.     

Raised and sunken bed land configuration for crop diversification and crop and water productivity enhancement in rice paddies of the north eastern region of India

Paddy and Water Environment - The crop and water productivity (WP) of monocropped rice in lowland of north-eastern region of India is low mainly due to cultivation of long duration variety, meagre...     

Micro paddy lysimeter for monitoring solute transport in paddy environment

The micro paddy lysimeter (MPL) was developed and evaluated for its performance to simulate solute transport in paddy environment under laboratory conditions. MPLs were constructed using soil collected from Field Museum Honmachi of Tokyo University of Agriculture and Technology, Japan. For the physical characteristics of the hardpan layer, parameters such as thickness, and soil aggregate size, affecting the percolation rate were studied. For the plow layer, two types of plow soils, sieved and un-sieved soils were compared. The sieved soil plow layer was produced by mixing air-dried soils of different aggregate sizes of D > 9.50, 9.50 ≥ D > 4.75, 4.75 ≥ D > 2.0 mm and D ≤ 2.0 mm at 47.1, 19.5, 20.6, and 12.8%, respectively. The un-sieved plow layer soil was directly used after collecting from the field. Inert tracer was applied to ponding water with controlled boundary conditions to evaluate the reproducibility of the soil hydraulic characteristics. HYDRUS-1D was used to evaluate the movement of bromide tracer in the MPL. The proposed conditions of the MPL were that the hardpan layer can be made from soil aggregates smaller than 0.425 mm with 2 cm thickness and that the plow layer can be prepared with sieved or un-sieved soils. With these conditions, the obtained results proved that MPLs can be a useful tool to simulate solute transport in paddy environment.     

Effect of irrigation and nitrogen fertilization on biomass yield and efficiency of energy use in crop production of Miscanthus

The perennial C₄ grass Miscanthus has been proposed as a biomass energy crop in Europe. Effects of crop age, irrigation and nitrogen fertilization on biomass and energy yields and N content of Miscanthus were investigated and the energy costs of production determined. After an establishment period of 1 year, cultivation of Miscanthus resulted in a dry matter production of over 37 t ha⁻¹ year⁻¹ over a period of 4 years. Irrigation and nitrogen level greatly affected Miscanthus biomass yield. In absence of N fertilization, irrigation did not modify biomass yield and the effect of irrigation increased with the increase in N level. The average N response ranged from 37 to 50 kg biomass kg⁻¹ N applied. Because the calorific value of Miscanthus biomass (16.5 MJ kg⁻¹) was not affected by irrigation and N fertilization, energy production depended exclusively on biomass yield. Maximum energy yield was 564 GJ ha⁻¹ year⁻¹. Without N supply and irrigation, energy yield was 291 GJ h⁻¹. Net energy yield, calculated as the difference between energy output and input, but without inclusion of drying costs, was 543 GJ ha⁻¹ with N fertilization and irrigation and 284 GJ ha⁻¹ without; the ratios of energy output to input in crop production were 22 and 47, respectively.     

Impact of crop and nutrient management on crop growth and yield,nutrient uptake and content in rice

Paddy and Water Environment - System of rice intensification (SRI) together with appropriate nutrient management holds promise in increasing rice productivity with micronutrient enriched grains....     

Bioefficacy and fate of fipronil and its metabolites in basmati rice under sub-tropical climatic conditions

Fipronil is a systemic insecticide having persistence in the plant system and is used for the management of the yellow stem borer, Scirpophaga incertulas (Walker), and leaf folder, Cnaphalocrocis medinalis (Guenee). The nature and amounts of active metabolites of fipronil used in basmati rice are set to ensure the safety of the consumers and the environment. The bioefficay, persistence and metabolism of applications of fipronil (Regent 0.3G) at 45 (recommended dose) and 180 (higher dose) g a.i. ha⁻¹ thirty days after transplanting of a basmati crop were studied. The fipronil gave long term insecticidal effectiveness for managing the stem borer and leaf folder at the tested doses on basmati rice throughout the cropping season. For residue analysis, samples of basmati rice plants were collected at 7, 15, 30, 45, 60, 90 and 120 days after application of the insecticide. Samples of basmati grains, bran, husk and straw were collected at harvest. After extraction and cleanup, fipronil and its metabolites were quantified by gas liquid chromatography (GLC) and confirmed by gas chromatography mass spectrometry (GCMS). The residues of fipronil and its metabolites were at a maximum at seven days after application, declining thereafter. Fipronil dominated as the parent compound and among the metabolites, the sulfone derivative was the most dominant followed by the sulfide, amide and desulfinyl, which were found below determination limit (0.01 mg kg⁻¹) 45 and 90 days after the application of fipronil at recommended and higher dose, respectively. The samples of basmati straw, grains, bran and husk at harvest time did not contain any detectable residues of fipronil or its metabolites.     

Relations of rice seeding rates to crop and weed growth in aerobic rice

Aerobic rice describes a management adaptation to reduced irrigation water supplies but, due to reduced intervals of flooding in this system, this requires revised weed management approaches to reduce costs and provide effective weed control. One approach is to make the crop more competitive and reduce the effects of weeds on the crop by using higher rice seeding rates. A study was conducted in the Philippines and India in 2008 and 2009 to assess the relations of seeding rates (15-125 kg ha⁻¹) of hybrid and inbred varieties to crop and weed growth in aerobic rice. Plant densities, tillers, and biomass of rice increased linearly with increased in seeding rates under both weedy and weed free environments. Weed biomass decreased linearly with increasing seeding rates from 15 to 125 kg ha⁻¹. Panicles and grain yields of rice in competition with weeds increased in a quadratic relation with increased seeding rates at both locations; however, the response was flat in the weed free plots. A quadratic model predicted that seeding rates of 48-80 kg ha⁻¹ for the inbred varieties and 47-67 kg ha⁻¹ for the hybrid varieties were needed to achieve maximum grain yield when grown in the absence of weeds, while rates of 95-125 kg seed ha⁻¹ for the inbred varieties and 83-92 kg seed ha⁻¹ for the hybrid varieties were needed to achieve maximum yields in competition with weeds. On the basis of these results, seeding rates greater than 80 kg ha⁻¹ are advisable where there are risks of severe weed competition. Such high seeding rates may be prohibitive when using expensive seed, and maximum yields are not the only consideration for developing recommendations for optimizing economic returns for farmers. Results of the present study do suggest however that increasing seeding rates of aerobic rice does suppress weed growth and reduce grain yield losses from weed competition. This information could be incorporated in integrated crop management packages to manage weeds more effectively.     

Effects of crop establishment techniques on weeds and rice yield

Field and pot studies were conducted to evaluate the effects of seven rice establishment techniques {puddling transplanting (PT), no tillage transplanting (NTT), puddling drum wet seeding (PDWS), no tillage drum wet seeding (NTDWS), conventional tillage dry drilling (CTDD), furrow irrigated raised beds system dry drilling (FIRBSDD), and no-tillage dry-drilling (NTDD)} and water submergence stress on weeds and rice yield. The highest yield and least weed abundance were in the PT treatment. The direct seeded rice (DSR), both dry and wet exhibited severe weed infestation, and compared to transplanting showed reduced yield both in the presence and absence of weeds. The yield losses due to weeds in the DSR treatments ranged from 91.4 to 99.0%, compared to 16.0 and 42.0% in the transplanting treatments (PT and NTT). Weeds, including Cyperus rotundus L., Dactyloctenium aegyptium (L.) Willd., Digera arvensis Forsk., Phyllanthus niruri L., and Trianthema portulacastrum L. which were found in the un-puddled DSR treatments were absent in the puddled plots, particularly the PT treatments. In pot studies, continuous water-submergence (2.5 cm) for 20 days reduced the emergence of C. rotundus, D. aegyptium, T. portulacastrum, and Echinochloa crus-galli (L.) Beauv. by 99.4, 100, 100, and 24.4%, respectively, compared to alternate wetting–drying. In farmer's field studies, when compared to the PT treatments, the DSR treatments exhibited lower yields (15.8%) with coarse varieties (HKR-47 & IR-64), but fine cultivars (Sharbati & PB-1) exhibited similar yields under both systems. In view of the shortage of labour for manual transplanting, there is a need to develop suitable cultivars for aerobic system conditions (unpuddled DSR and NT machine-transplanting).     

丘陵区水稻品种多样性混合间栽控制稻瘟病研究

在对 2个主栽品种 (生产上推广的当家杂交稻组合 )和 2个间栽品种 (优质感瘟 )进行 RGA遗传背景研究的基础上 ,配成 4个混合间栽组合。经在祁东 (丘陵 )小区试验和示范比较 ,结果都表明品种混合间栽后 ,间栽品种叶瘟的防治效果达 48.86 %～ 79.91% ,穗瘟的防治效果达 12 .38%～ 6 3.5 7% ;混合间栽的主栽品种与净栽主栽品种比较 ,叶瘟和穗瘟的病情严重度差异不大。在产量上 ,混合间栽比净栽均表现出不同程度的增产 ,幅度在 1.5 7%～ 12 .71%。基于本研究结果 ,选择抗瘟性遗传背景差异大 ,株高差异突出的品种以 1行优质稻间 5行主栽品种混合栽培 ,能起到控瘟增产的作用。     

Influence of nitrogen fertilization on some nutritional quality characters in rice

The influence of three levels of nitrogen fertilization on the grain yield, protein and starch make up of three varieties of rice: IR-8, Sabarmati, and Basmati-370, was studied in a field experiment. Part of the nitrogen was applied through foliar spraying at the time of anthesis. The grain protein and amylose content of developing caryopsis was studied. Significant increase in yield and crude protein content was recorded but the amylose content decreased slightly with increased nitrogen fertilization. Five of the essential amino-acids, reported, increased with fertilization. Lysine content increased steadily when expressed on protein as well as meal basis. Contrary to the expectation, the two dicarboxylic amino acids did not increase significantly.     

Modeling the dependence of the crop calendar for rain-fed rice on precipitation in Northeast Thailand

Rain-fed lowlands are major agricultural ecosystems used for rice production in Northeast Thailand. Developing a tool to assess the effects of variable water conditions on the regional scale yield is also important to predict the effects of climate change on food supply. To estimate regional yields, we need a simple but accurate measure of the crop calendar (i.e., the distribution of planting dates), which has a strong influence on grain yield. In this article, we modeled the dependence of the crop calendar on rainfall patterns based on a survey of the region’s farmers as a part of an effort to provide a stronger basis for regional yield estimates. Our survey, conducted in 11 provinces for 2 years, confirmed the existence of large windows for sowing and transplanting versus narrow windows for heading and harvesting for rain-fed lowland rice culture in all the provinces. Variable water, soil, and toposequential conditions in the paddy fields were responsible for the large sowing and transplanting windows, whereas the use of photoperiod-sensitive varieties explained the narrow windows for heading and harvesting. The crop calendar was well expressed as a function of cumulative precipitation from June onward. When the crop calendar model was combined with a simple phenology-based model that uses growing degree-days adjusted by a day-length factor, we could estimate the rice crop calendar under rain-fed lowland conditions with acceptable accuracy. The model described in this article will be combined with a crop growth model to improve regional yield estimates for rain-fed lowland rice.     

Arsenic-prone rice cultivars: a study in endemic region

Rice is prone to arsenic accumulation compared to other cereals as typically grown up under waterlogged situation favoring arsenic mobility. Arsenic in rice depends on arsenic availability to plants from irrigation water, even differs among cultivars and their plant parts. Present study was concentrated on arsenic accumulation in various plant parts of five common rice cultivars grown using irrigation water from different water sources in various fields in arsenic-endemic region. Additionally, dose response experiment under laboratory net house was conducted on the same cultivars excluding open environmental factors. The common cultivars were categorized according to high to low arsenic accumulator in rice grain, straw and root parts. The cultivar Shatabdi has shown highest arsenic accumulation in rice grain compared to other rice cultivars in fields and when grown at various soil arsenic doses. In field samples, a highest grain arsenic concentration ranged between 0.69 ± 0.04 and 0.78 ± 0.12 mg kg^?1 for Shatabdi, whereas lowest grain arsenic concentration ranged between 0.37 ± 0.07 and 0.41 ± 0.07 mg kg^?1 for the cultivars GB3 and Lalat. Speciation study detected more inorganic arsenic than organoarsenicals with a trend of arsenite > arsenate > DMA > MMA, which would be problem for consumers. The concluding remark is the characterization of common rice cultivars according to arsenic concentration to highlight an important remediation strand by changing to low arsenic cultivar.     

Water use in rice crop through different methods of irrigation in a sodic soil

Sodic soils are characterized by high exchangeable sodium on exchange sites, soil pH greater than 8.5, relatively low electrical conductivity, low infiltration rate and dispersed clay. These characteristics restrict the capacity of soil to absorb water, resulting in poor infiltration. Evidently, these soils require application of irrigation water at shorter intervals for crop production. Thus, irrigation strategy for sodic soils differs from that of normal soils. An experiment to determine the suitable irrigation strategy along with methods of application namely: surface (farmer’s practice), sprinkler (double nozzle impact sprinkler), and low-energy water application device (LEWA) were initiated in the year 2012 for rice crop. Irrigation depths of 6 cm in case of surface method and 4 cm in case of sprinkler and LEWA methods were applied at each irrigation event. The irrigation events for rice were scheduled at 2-DAD (days after the disappearance of the ponded water), 3-DAD, and 4-DAD through surface method, and at daily, 1- and 2-day intervals (after initial ponding disappeared) by sprinkler and LEWA methods. Sprinkler and LEWA methods resulted in highest rice yield of 4.4 t ha^?1 in irrigated plots at the 2-day interval which was at par with the highest yielding surface-irrigated plot scheduled at 2-DAD. At the same time, irrigation strategy of 2-day interval through sprinkler and LEWA methods registered water saving to the extent of 30–40% over 2-DAD under surface irrigation method. Results revealed that there could be substantial saving of water and energy (electricity and diesel) through the use of sprinkling devices for irrigating rice under sodic soil environments.     

施肥方式对超级杂交稻产量及效益的影响

为研究与超级杂交水稻良种相匹配的强化栽培技术,2004年在湖南浏阳开展了不同施肥方式对超级杂交稻产量及效益影响的研究.结果表明,每公顷施N 187.5 kg,N,P,K总量440.1 kg,N:P:K=1:0.56:0.56能获得最高的产量和效益,投入产出比则以每公顷施N 106.5 kg,N,P,K总量274.5 kg,N:P:K=1:0.79:0.79的方式为最高.     

豫南稻区不同施钾水平对作物产量效应影响

对豫南稻区不同施钾处理在水稻、小麦和油菜三种作物上的产量效应进行了田间试验研究。结果表明,施钾处理增加效果明显,其中稻田和麦田施钾124.5kg/hm2处理,油菜田施钾186.75kg/hm2处理与对照相比增产效果最明显。水稻、小麦、油菜分别在施钾146.6kg/hm2、145.6kg/hm2、183.6kg/hm2时的产量最高,单位面积产量分别为6869.3kg/hm2、3517.1kg/hm2、2424.2kg/hm2。     

两优培九单晚种植的高产特点及栽培技术

两优培九是由江苏省农科院和国家杂交水稻工程技术研究中心合作育成的两系杂交籼稻组合。2000年引入江山市试种 ,2002年全市种植面积0.3万hm2,占单晚面积的44.98 % ,预计2003年将进一步扩大种植 ,成为江山市单晚的当家品种。据两年的调查显示 ,两优培九在江山市常规栽培单产仅为550kg/667m2 ,相当于示范片中低产田产量。这说明当地多数农民并未真正掌握两优培九组合的高产特点和栽培技术 ,有必要作进一步的探讨。一、两优培九的生育期及适应性经江山市2年的试验观察认为 ,两优培九感温性强、感光性不及协优9308组合 ,早播早成熟 ,全生育期14…     

油茬田免耕直播水稻施肥量的研究

2002～2003年在石门县进行了油茬田免耕直播水稻栽培试验,比较研究了5种不同施肥量对培两优93和两优培九的生育期、株高、总叶片数、茎蘖动态、产量和产量构成的影响.结果表明油茬田免耕直播水稻的适宜施肥量为750～900kg/hm2缓释肥.     

SRI as a methodology for raising crop and water productivity: productive adaptations in rice agronomy and irrigation water management

The System of Rice Intensification (SRI), developed in Madagascar almost 30 years ago, modifies certain practices for managing plants, soil, water, and nutrients with the effect of raising the productivity of the land, labor, and capital devoted to rice production. Certain production inputs are reduced—seeds, inorganic fertilizer, water, and fuel where water is pumped—with increased yield as a result. This paper introduces the subject of SRI, which is then addressed variously in the articles that follow. SRI is gaining interest and application in over 40 countries around the world. Its practices make soil conditions more aerobic and promote greater root growth, as well as larger, more diverse communities of beneficial soil biota. These below-ground changes support more productive phenotypes above-ground for practically all rice genotypes (cultivars) tested so far, with supportive evidence accumulating both from scientific institutions and field applications. SRI methodology remains controversial in some circles, however, because of the transformational change it introductions into traditional lowland rice production systems. This issue of PAWE brings together the results of formal research on SRI in a number of countries (Part I) and also reports on initiatives by government agencies, NGOs, universities, or the private sector, bringing knowledge of SRI to farmers in a wide range of agroecological circumstances (Part II). This introduction presents the basic principles that underlie SRI and discusses the nature of this innovation as well as considers some of the issues in contention. SRI continues to evolve and expand, being a work in progress. Its concepts and methods are being extended also to upland (rainfed) rice production, as well to other crops. Accordingly, SRI should not be regarded or evaluated in conventional terms as if it were a typical component technology. It is understood more appropriately in terms of a paradigm shift for rice production. In particular, it calls into question the long-standing belief that rice is best produced under continuously flooded conditions.