Short-term Crops Research Articles

Benefits of biochar over other organic amendments: Responses for plant productivity (Pelargonium graveolens L.) and nitrogen and phosphorus losses

Biochar is considered a promising option for soil fertility improvement, little is known about its advantage and profitability over other organic amendments in terms of nutrient losses/harvest and plant productivity for short-term crops. A field trial of geranium (Pelargonium graveolens L.) was conducted using farmyard manure, vermicompost, and biochar with and without inorganic fertilizers. Nitrification, ammonification, phosphorylation, N2O emissions, nitrogen, and phosphorus used efficiencies along with crop productivity were examined for each treatment. Results indicated that addition of farmyard manure, vermicompost and biochar reduced nitrogen and phosphorus losses. The improved nutrient efficiencies by organic manure led to increasing the productivity of the geranium crop. Among three organic manures, biochar had the lowest losses to harvest nutrient ratio (0.39–0.69). Vermicompost treatments demonstrated the highest losses to harvest nutrient ratio (1.24–3.25). The budget estimates using nutrient loss, damage cost, and plant productivity implied that biochar addition in the sole and in combination with inorganic fertilizers was economics for farmers. However, vermicompost and farmyard manure were also profitable in sole treatments. The combined treatments of farmyard manure and vermicompost were not economic due to higher nutrient losses and their environmental impact. The conversion of organic waste to biochar could be the more promising option for the reduction of nutrient loss, damage cost, and plant productivity in sustainable agriculture.

Short-Term Effects of Different Organic Amendments on Soil Fungal Composition

Fungi play an essential role in recovering the quality and fertility of soil. There is a limited understating of the complex response of fungal diversity to different organic materials in clay loam soil. Here, we report the response of soil fungi toward the short-term application of manure (M), sugarcane straw (S), and sugarcane straw plus manure (MS), including no organic material control (CK) at two different time points (50 and 100 days after application). Illumina sequencing was used to examine the fungal communities. Our results reveal a significant shift among the soil fungal community structure associated with each organic material application. After both time points, amendments—especially M and MS—decreased the fungal richness and stimulated the copiotrophic fungal group (Ascomycota) compared to the control soil (CK) and S-amended soil. On the contrary, as compared to the M and MS-amended soils, the CK and S-amended soils at both time points increased the fungal richness and stimulated the oligotrophic fungal groups. Organic material use, especially M and MS, showed variable results regarding pathogenic fungi enhancing the abundance of Lophodermium and Cercophora and decreasing Fusarium. Concerning the abundance of plant-beneficial fungi, Mortierella was reduced, and Podospora was increased by M and MS input. FUNGuild showed that the amendment of organic materials efficiently declined the abundance of endophytes and plant pathogens, but also enhanced the animal pathogens in terms of abundance with respect to CK at two time points. This study could be useful to provide a novel understanding of the management of soil-borne pathogens by organic amendments for the sustainable production of short-term crops.

POTENSI PEMANFAATAN LAHAN TIDUR DI KABUPATEN KERINCI

Abstract: Abstract: Land in Kerinci is still classified as fertile and productive to be processed into farming activities. The purpose of this study was to find out the potential utilization of sleeping land in Koto Tuo Ujung Pasir Village, Lake Kerinci Subdistrict, Kerinci Regency and find out suitable agricultural processing solutions for sleeping land in Koto Tuo Ujung Pasir Village, Lake Kerinci District, Kerinci Regency. This research belongs to the type of quantitative research. Research subjects included: farmers and community members around the sleeping area. The sampling technique used in this study was purposive sampling. Researchers used interactive models from Miles and Huberman in analyzing data. Utilization of sleeping land potential can illustrate the following conditions: 1) internal factors indicate the availability of skilled and experienced workforce to process land, whereas in external factors sales are obtained in addition to farmers' income which is supported by the desired yield of consumers; 2) creating markets and increasing product development on available land by cultivating more productive types of short-term crops; and 3) the prospect of exploiting the potential of sleeping land has a long-term advantage as a market transaction that results in the circulation of money in the community.

ACTIVITY OF CHESTNUT TANNINS AGAINST THE SOUTHERN ROOT-KNOT NEMATODE MELOIDOGYNE INCOGNITA

Studies on the effects of tannins on plant-parasitic nematodes are few. A new formulation of a hydrolysable tanninextracted from chestnut (SaviotaN®) was tested for efficacy in controlling Meloidogyne incognita. Therefore, in vitro andpot experiments on tomato were performed to investigate the nematicidal activity of tannin aqueous solutions at differentconcentrations on M. incognita. In the in vitro experiment the following concentrations of tannin at 0.30, 0.40, 0.50, 0.75,1.00, 1.25, 1.50 g L−1 were tested for their effect on the nematode. The second-stage juveniles (J2s) immobility increasedwith increasing concentration and exposure time. All tested tannin concentrations were effective to reduce viability fromabout 45 to 70% after 10 days of exposure, in comparison to the treated and untreated controls. The immobile J2s recoveredtheir mobility over time after rinsing and transferring them in water, showing a nematostatic activity of tannins. In the potexperiment, tannins, as aqueous solutions at rates from 0.30 to 1.50 g L−1, were applied to soil at three different applicationtimes (1: only at transplant; 2: at transplant, two weeks after transplant and repeated every seven days; 3: at transplant andtwo weeks later). The activity of tannins was compared to treated and untreated controls. Tested rates mostly repeated wereeffective to control nematode attack in comparison to untreated control. The height of treated plants was not significantlyinfluenced by the different applied rates of tannins, whereas nematode population density and root galling index wereaffected by repeated application times. No visual symptoms of phytotoxicity were detected. The use of SaviotaN®appearspromising for the control of M. incognitain sustainable agriculture of short-term crops and/or when nematode populationdensities are low and as a supplement to other chemical treatments.

Effect of Land related Factors on Smallholder Cropping Systems in Rural Sri Lanka

There are marked differences between the Wet and Intermediate Zones of Sri Lanka in the type of crops selected and cropping practices used by smallholder farmers. This study was specifically geared to i) identify the major smallholder cropping systems in the study area, ii) analyze the relationship between land size and cropping intensity, and iii) to determine how land size, land ownership, proximity to land from the homestead influences the selection of different cropping systems. Data and information were collected from a sample of 96 households in the four selected villages representing each from Kalutara, Kegalle, Moneragala and Hambanthota districts using semi structured interviews, direct observations, case studies and farm sketches. Data were analyzed using a variety of statistical methods including chisquare and general linear model. The study found that the allocation of land for the selected crops was lower in the villages of Kegalle and Kalutara districts compared to the Moneragala and Hambanthota. The study also ascertained that an increase in land size resulted in a decrease in the number of crops grown and cropping intensity in home gardens and rubber smallholdings. Also lower priority was given to intercropping of rubber smallholdings by farmers owned with more than 2 acre of land available, and vice versa. The income level of the household had a considerable influence on several factors including, selection of cropping systems, size of land holding, and allocation of land to different crops. Variation in land ownership between villages had a significant effect on the establishment of crops (p<0.001) i.e. owner-cultivated smallholdings comprised a mixture of many short term and permanent crops while tenant cultivated smallholdings consisted solely of short-term crops. Distance of the land from the homestead had a significant effect on the selection or non-selection of cropping systems. Consequently, crops with less risk and maintenance were grown further out from homestead (e.g. citronella) and rubber compared to banana and tea. Similarly, the form of land smallholdings consisted of a mixture of intercrops (including other permanent crops), and soil protection methods were practiced, whereas tenanted farms had seasonal intercrops with less attention paid to soil protection and improvement. KEYWORDS: Land ownership, Proximity, Land size, Smallholders, Cropping systems

Climate Variability and Its Effects on Gender and Coping Strategies in Baringo County, Kenya

Climate variability has often been described as one of the most pressing environmental challenges. Our lifestyles, economy, health, income, livelihood and our social well-being are all affected by climate. This paper therefore, assessed climate variability, its effect of gender and coping strategies they adopt in Baringo County, Kenya. Descriptive and inferential statistics were used in analyzing the data obtained for the study. Findings show that there is consisent decrease in rainfall and increase in temperature in recent times. Male gender dominates household decisions and roles such as land preparation, livestock keeping/feeding, pesticide application and fence construction in Baringo County, Kenya while the female gender dominates household roles such as water supply, domestic home chores and more of agricultural activities. Livestock migration was the major traditional coping strategy adopted in Baringo County. 56.8% of the respondents shows that cutting grasses for livestock was the major short term coping strategy adopted while Rainfall harvesting and storage (5.92%) was the least adopted in the studied area. Long term coping strategy to climate variability mostly adopted by the rural populace in is livestock migration (48.52%), it was also observed here that the least long term coping strategy adopted is finding alternative job as reputed by 4.44% of the respondents. Special intervention projects such as rain water harvesting techniques, drought resistant crops, short term crops etc, should be provided to rural populace/dwellers in Baringo County, and other parts of Kenya experiencing severe variability in climate, resulting to drought.

IMPLEMENTING DATA SCIENCE FOR RAINFALL PREDICTION WITH VARIABLE PARAMETERS THROUGH MACHINE LEARNING AND ADVANCED BIG DATA TOOLS.

India is an agriculture based country. Most of the population is living in villages and their occupation is agriculture. As Mahathma Gandhiji said “The Development of the nation is depends on the development of the villages”. Rainfall is most required factor for agriculture. The complete agriculture depends on Rainfall [2]. Due to abnormal conditions of the weather the formers are forgoing their crops and indulging as debtors. Most of the farming areas in the country are depends on the Rainfall, In India only 34% of the fertile land getting water through the rivers . So there is a huge necessity for Prediction of Rainfall. The Rainfall is one the most important Phenomena of the weather. The weather may be described as change-in-climate. Rapid changes occurred in the weather. It is the major task to understand and predict the weather. The weather parameters are • Temperature • Humidity • Wind speed • Wind direction • Rainfall • Pressure The major occupation of the Indian people is Agriculture. Rainfall plays a major role in agriculture. The prediction of rainfall helps the farmer to decide the type of a crop. The crops broadly categorized in to 2 types. 1) Short Term crops 2) Long Term crops Short Term Crops: The short term crops required less water and the crop completes with in the short period. Eg: Leafs, Long Term Crops: The long term crops required more water and the crop takes long period such as 3 months, 6 months, 1 year etc. Most of the crops are depends on Rainfall. So the prediction of rainfall helps the farmers to decide the type of crop.

Đánh giá tiềm năng suy giảm độ phì nhiêu đất tỉnh An Giang

The objective of the study was to assess the soil fertility degradation for the period of 2012-2016 and to show the changes in chemical properties in terms of spatial distribution and land use types. It also helped managers to propose effective measures to reduce and improve soil fertility degradation having been happening in the area. The study used a set of properties from background data to assess the degree and extent of soil fertility degradation on the basis of comparison with the soil samples analysis results at the same site or the same soils that are nearest to the location such as soil pH, organic matter (OM), cation exchange capacity (CEC), total nitrogen (N), total potassium (K), and total phosphorus (P). The result showed that the total area of the province had 112,321.38 hectares of soil with degraded fertility, occupied 40.21% of the surveyed area, and the land area without degraded fertility was 167,025 hectares, occupied 59.79% of surveyed area. In general, the soil fertility degradation in the province was light, but the soil chemical properties had significantly decreased in cultivated areas such as intensive rice cultivation in dike areas, short term crops growing areas, and forest soil in the low mountainous with have steep slope.

Early growth of rubber in the Dry Zone of Sri Lanka: an investigation in Vavuniya District

In view of supporting the rubber product manufacturing sector in Sri Lanka and providing stable income for the peasant community, rubber cultivation is in the process of expanding to the drier regions of the country. Under this programme, rubber was introduced to the Northern region (Dry Zone) in 2010 with a tentative set of agronomic protocols. The present study showed that rubber cultivated in this region under smallholder conditions together with irrigated short term crops, has shown reasonable growth with an average annual girth expansion rate of 8.6cm. A growth curve for the immature phase of rubber was established for the first time for the dry zone of Sri Lanka. Despite some adverse effects of dry weather on photosynthesis and associated physiological parameters, no evidence of permanent damages to photosynthetic apparatus was recorded. Further actions to be taken in the expansion process of rubber cultivation in this region are also discussed.

Evaluation of groundwater pollution risk (GPR) from agricultural activities using DRASTIC model and GIS

Groundwater Pollution risk (GPR) map which utilized groundwater quality is important in order to prevent the groundwater contaminant concentration due to the agricultural activities. DRASTIC model and GIS application are two important tools that had been used for accessing and predicting the quality of groundwater. These supplementary tools are calculating, visualizing, and presenting the GPR by using DRASTIC index for each hydrogeologic factor through ArcGIS software. This study was covered approximately Selangor basin area where the GPR has been defined. There are four categories of agricultural activities in the Selangor basin which are animal husbandary areas, horticultural lands, short term crops and tree, palm and other permanent crops. The map showed that the “low” zones of GPR occupied 56% of the east side of the Selangor basin, 34% of the west side of the Selangor basin exposed to “medium” zones of GPR and the “high” zones of GPR covered 10% at the north side and the south to the west side of the Selangor basin. As a particular, for agricultural activities which is 52% of Selangor basin area, the “low”, ‘’medium” and “high” zones of GPR was occupied as 42%, 43% and 15% respectively. Based on four categories of agricultural landuse, GPR map validated by nitrate distribution map, shows that the 99% of the variation in nitrate distribution zones are explained by GPR zones. In conclusion, groundwater pollution risk was affected by agricultural activities.

Biomass and Carbon Stock Estimation Inventory of Indonesian Bananas (Musa spp.) and Its Potential Role for Land Rehabilitation

ABSTRACTBananas (Musa spp.) are widely cultivated in Indonesia. They are extensively grown in backyards, homegardens, intercropped with short term crops and also in agroforestry system. Potential role of bananas to absorb and store Carbon related to climate change mitigation is rarely studied. An inventory of biomass and C-stock estimation on banana accessions has been conducted in Musa germplasm plots - Purwodadi Botanic Garden, Pasuruan. 42individual banana accessions has been estimated its biomass and C-stock comprises of 5 wild types and 37 cultivars. Biomass estimated using non-destructive method ie. allometric equation for banana by measuring its mature stage pseudostem diameter at breast height (dbh). C-stockwas estimated by crossing its biomass to averaged value of banana C-stock 0,46.The results showed that the biomass and C-stock estimation level were in positive correlations with its plants pseudostem dbH. The conclusions of these research that Kepok Bung cultivar has the highest level of estimated biomass and Carbon stock about 15, 02 kg/plant and 6, 92 kg C/plant and then cultivars with range averaged C-stock between 3,5 – 3,9 kg C/plant (higher level) are Tlekung, Baflo, and Cici. Musa balbisiana species contributes higher level of biomass and C-stock estimation than Musa acuminata species.Keywords: Banana, biomass, carbon stock (C-stock), estimation, Musa, non- destructive, Purwodadi Botanic Garden               Â

Evaluation of the fertilizing effect of olive mill waste compost in short-term crops

Recycling to soil Olive Mill Waste (OMW) has the potential to improve soil fertility, thus reducing CO 2 emission associated to global warming. However, the short period in which OMW are produced and the high load of recalcitrant compounds, make difficult direct land spreading of raw OMW. Consequently, sustainable biological treatments able to transform OMW into a safe amendment have been progressively developed. In comparison to a standard mineral fertilization, the present work assessed the agronomic performance of two innovative kinds of OMW compost, used as fertilizers in Lactuca sativa and Lycopersicon esculentum cultivation trials. Both crops showed yields comparable to control, thus suggesting that most of the nutrients contained in the OMW supported adequately plant growth, even in short-term crops. Six months later OMW application, no significant differences were found in the soil humic content.

Diseases of Tropical Perennial Crops: Challenging Problems in Diverse Environments.

The world’s oldest ecosystems are found in the tropics. They are diverse, highly evolved, but barely understood. Diseases that impact crops in these regions can be significant contraints to production, especially when they occur in lowland environments with high rainfall and uniform, warm temperatures; respites from disease pressure there are often infrequent. Difficulties in managing diseases in the humid tropics are multiplied when the affected crops are perennial. The favorable conditions for disease development and the presence of susceptible host tissue over long periods make diseases of tropical perennial crops serious management challenges. This topic is introduced with a few concepts on the occurrence and development of these pathosystems. Peculiar aspects and scenarios that influence the types of and extent to which different diseases develop are summarized. Measures that are useful on annual or short-term crops may be ineffective against these diseases. They are scientifically interesting problems. New vectors, as for mango malformation, or pathogens, as for bunchy top of papaya, are associated with some of the diseases. And some of the diseases are caused by two or more distinct taxa; for example, citrus greening, mango malformation, Panama disease, and tracheomycosis of coffee. Some of the most important diseases are host-specific and are caused by either coevolved or new-encounter pathogens. Resistance, the most effective tool with which many of these diseases are managed, is usually available in coevolved pathosystems but may be uncommon in new-encounter situations. Inadequate host resistance can be a significant barrier in the management of both coevolved and new encounter diseases. General tactics are described that are useful against diseases of tropical perennials. The successful management of plant disease utilizes several principles and practices, regardless of the host and environment in which it is grown. These include the avoidance, exclusion, and eradication of the causal agents. Host protection is of great importance, as is the identification and incorporation of resistance in the host plant. All of these approaches are discussed with tropical perennial examples.

Effects of wilting and lactic acid bacteria inoculation on fermentation quality of white lupin and fababean silages

Fababeans and lupins are short-term catch crops with a high crude protein content, which provide a high forage yield in a short growing period. Legumes are difficult to conserve as silages because of their low water soluble carbohydrates content (WSC) and high buffer capacity. To our knowledge, little information is available on the ensiling of fababeans and lupins in Southern Europe. The research was carried out in Lodi (Italy) in order to evaluate the effects of wilting and inoculation with lactic acid bacteria (LAB) on fermentation characteristics of the resulting silages. The data show that both wilting and LAB inoculant significantly improved fermentation quality of the legumes silages.

The growth and yield of rubber at maturity is improved by intercropping with banana during the early stage of rubber cultivation

Abstract Intercropping with short-term crops provides a significant additional income during the long immature period of rubber tree growth when no latex is produced. Much previous evidence has demonstrated that the growth of young rubber trees is unaffected by the presence of an intercrop. However, few, if any studies have however been conducted to date to assess the effects of intercropping on subsequent growth and yield of rubber once the companion intercrop is removed. This study demonstrates for the first time that intensive intercropping of young rubber with banana may result not only in a sustained increase in growth and yield of rubber trees but also a reduction in the length of the unproductive immature phase. Rubber was grown either as a sole crop, or intercropped for the first 4 years with banana. The intercrop comprised an additive series of one, two or three rows of banana to one row of rubber. Growth of rubber was monitored for 6 years, i.e. up to the time that tapping for latex began and a logistic growth function was fitted to girth data in order to assess growth. Intercropping had a positive effect on the growth of rubber throughout the 6 years of the study, with the result that trees in the intercrop treatment were ready for tapping 4 months earlier than in the sole crop. Whilst girth and height were greater in the intercrops, bark thickness was similar to that of the sole crop. Intercrop treatments had no effect on latex yield per plant, but yield per hectare was greater in the intercrop than sole crop treatments due to a higher number of tappable trees.

Pest Control in Malaysia's Perennial Crops: A Half Century Perspective Tracking the Pathway to Integrated Pest Management

Leaf eating insect outbreaks of unprecedented severity occurred on oil palms and cocoa in what became Malaysia, from the late 1950s to early 1960s. Growers faced two crucial questions, what to do about the attacks, and what caused them. The tropical climate generally continues suitable for phytophagous insects to realise their large increase capacity, a factor emphasised in the stable agroecosystem of perennial tree crops. Parasitic and predatory natural enemy insects are equally favoured and maintain control. It became increasingly evident that the prime cause of outbreak was disruption of this balance by the introduction of broad spectrum, long residual contact insecticides (bslrcs), with various contributory factors. Patchy pesticide residues would continue to eliminate inherently exploratory parasitic and predatory insects, something worsened by uneven initial application. In these conditions, there is a complete overlap of generations of both pests and enemies, with no evolution of synchronised or otherwise coordinated life cycles (‘continuous generation mode’– CGM). In outbreaks the pests tend to be at a similar lifecycle stage (‘discrete generation mode’– DGM), so that at times a high proportion of an enemy population that may be building up cannot find a suitable host stage. Simply stopping application was often enough to end the vicious circle of treatment and reoutbreak, but also, commonly, there was heavy damage in the meantime. Selective application was developed, involving inherent pesticide characteristics or method of use opposite in at least one aspect to bslrc (i.e. narrow spectrum, short residue life, or non-contact). Large areas were treated, e.g., from the air. Infestations mostly disappeared with only one or a few applications. In that era of the 1960s, chemical application compatible with biological control was known as ‘integrated control’. The bslrcs had been introduced to control other regularly occurring pests (‘key’ pests), limited localised build up of the target pests e.g., from climatic fluctuations (‘occasional’ pest), or as a ‘precaution’. Some species only appeared after disruption started (‘potential’ pest). Development of selective chemical control continued to be for key and occasional pests, aiming at effective kill once decided upon. Census monitoring ensured application only when justified economically, with timing to the most vulnerable stage in the pest lifecycle. Among non-chemical approaches, cultural methods include provision of suitable flora in the ground vegetation for food sources for adult parasitic insects. Reasonably dense ground vegetation cover is grown to suppress rhinoceros beetle damage in oil palm replantings. Other possibilities include dissemination of insect diseases, traps and attractants, and resistant plant types. This fitted ‘pest management’ which by the mid-1970s came to encompass selective chemical use, as ‘integrated pest management (IPM)’. There were similar developments in other parts of the world, and in other perennial tree crops, extended also to short term crops (e.g., rice and vegetables). IPM is not an esoteric methodology awaiting ‘complete knowledge’. It can be applied on the basis of principle and existing knowledge for the most reliable economic control, targetted to encompass any aspect, such as toxicology and environmental effects.

A Study on Crop Residue Management to Maximize Nitrogen Recycling and Operating Efficiency.

Four operational methods were examined for a better managing of crop residue to maximize nutrient recycling and operating efficiency; leaving it on the field (LV), carrying it out of the field (CO), gathering it and burying it in ditches (GB), and pulverizing and spreading it on the field (PS). The PS method was the quickest for managing tomato plant residue, where the use of a flail mower was very efficient. There was quite a large quantity of tomato plant residue, containing 300kg N ha-1, which is sufficient to grow various kinds of crops. Furthermore, there was sufficient nitrogen for even shortterm crops like chingen-tsai. The growth and yield of two succeeding crops, chingen-tsai and to-tsai, were best by PS, while those by LV and GB were superior to the control, CO. Soil pH and nitrogen availability in the soil were high in the three plots incorporating the residue.Results show that recycling crop residue into the field significantly affects soil chemical properties and growth of succeeding vegetable crops.

PEOPLES PARTICIPATION IN FOREST RESOURCES DEVELOPMENT A CASE STUDY IN POLPITHIGAMA, KURUNEGALA

This paper illustrates the results of a study carried out by the Forest Department aimed at reestahlishmentof vegetation covers on state owned barren lands as well as under-developedprivate land through people's participation. The study area was at Polpithigama. inKuruncgala District situated adjacent to Pallekclc Forest Reserve (11.000 hectare) inKurunegala and Anuradhapura Districts. The settlers of Polpithigama are second and thirdgeneration families migrated from neighbouring villages within last 2-3 decades. Eight)'seven percent 01 villages were subsistence farmers. The majority belongs to underprivileged state 01 the society. Except the Funeral Aid Society. there were no other SOCIalorganisations. The management interventions of the Extension unit of the divisional forest office inKurunegala included formation of farmers organisations. block planting. homesteaddevelopment and nursery establishment Block planting. homestead development and nursery management were major activitiescarried out under this trial. Out of 127 farmers 76 participated in this programme and 38hectare of land was planted with Acasia oriculiformis. Sixty one (61 o/c) percent of blockswere successfully intereropped with vegetables, pulses and other short term crops. Totalseedling requirement (ISO.OOCll was provided by the village nursery maintained hy farmersociety. Land clearing, soil preparation, planting and other all activities were carried out bythe participation of the farmers and their families. Maintenance and protection were clone byfarmers. It was observed that the average income of farmer has increased by 37'lc during thefirst year and by 21St and IYlc during second and third years respectively. Sixty eightpercent of the farmers had developed their homesteads very satisfactorily. The observationshave revealed that. vegetation cover and soil fertility has improved and soil erosion is undercontrol. Micro-climate of the area also has changed desirably According to the estimates, Forest Department's contribution to the programme was Rs.294,000.00. Participants contribution was Rs.716,7X2.00 which included establishment andmaintenance costs for 3 years. Therefore this study clearly disclosed that i I the properextension programmes were conducted and farmers were motivated. it is possible to seekactive participation of farmers Ior development of forest resources.

A mycorrhizal pathogen ( Glomus macrocarpum Tul. & Tul.) of tobacco: effects of long- and short-term cropping on the mycorrhizal fungal community and stunt disease

A crop rotation experiment was conducted on two adjacent tracts of land differing in long-term croppin history (30 year in tall fescue pasture or 3 year in sorghum-sudangrass hybrid (SSGH).. Short-term crops were 2 years in tobacco or low-endophyte ( Acremonium coenophialum Morgan-Jones & Gams) tall fescue. Tobacco was grown on all plots in Year 3, and data relating mycorrhizal stunt disease of tobacco and populations of the stunt pathogen, Glomus macrocarpum Tul. & Tul., and of other members of the mycorrhizal fungal community, were taken. Disease incidence was highest with SSGH-tobacco and lowest with fescue-fescue, the other two combinations being intermediate. Mycorrhizal colonization was related to disease occurence. At the beginning of the season, populations of G. macrocarpum were equally high in land with a long-term history of SSGH, regardless of its short-term history; but at the end of the season, populations of G. macrocarpum among the four treatments were proportional to the incidence of disease. Populations of four mycorrhizal fungal species which were high in land with a short-term history of fescue were depressed by production of tobacco. Monocropping of tobacco appeared to narrow the diversity of the mycorrhizal fungal community and increased the proportion which is pathogenic, the overall result being lower productivity of soil for tobacco. Crop rotation of tobacco with fescue decreased the proportion of the mycorrhizal fungal community which is pathogenic and maintained productivity of soil for tobacco.

Modelling the intercropping of maize and beans in Kenya

Intercropping is a common practice on small farms in developing countries. In Kenya, where maize is the staple food, it is common to find maize intercropped with a range of short-term crops such as beans, sunflower, groundnuts, millet, potatoes. Competition between the crops for light, water and nutrients is possible at some stage in the production cycle, and field trials to measure the benefits of intercropping have been inconclusive. SODCOM has been used to analyse the intercropping of maize ( Zea mays) and beans ( Phaseolus vulgaris) in the Kitale region of Kenya. Three cropping situations have been examined: maize alone, beans alone and maize intercropped with beans. The model incorporates modifications which take account of the competition between the intercrops for light and water. The predictions of intercropped yield from the model are found to be in reasonable agreement with the results of field trials among small farmers in the Trans Nzoia District of Kenya over a period of 7 years. Comparing the yields obtained under intercropping with what would have been obtained with both crops grown in pure stands, intercropping has only a minimal effect on the yields of either crop. The yield of the maize, which has a longer growing season than the beans, was found to be sensitive to the degree of moisture stress, which was likely to occur towards the end of the growing season. The main argument against intercropping is that it limits the opportunities for mechanisation beyond seed bed preparation and drilling.