Scientific abstracts

Relationship between Chloride Salts of Sodium and Potassium with Seedling Growth of BRRI dhan 41

A laboratory experiment was conducted at Agronomy Laboratory of Agrotechnology Discipline, Khulna University, Khulna, Bangladesh during 10 September to 1 October 2008 to determine relationship between chloride salts of sodium and potassium with germination and seedling growth of BRRI dhan 41. Potassium chloride and sodium chloride were used as two salt sources and each sources had five different levels of salt viz. 0, 75, 150, 225, and 300 mM. Data were collected on germination percentage, energy, capacity & speed and the length of root and shoot length as well as dry weight of root and shoot per plant. There were wide variations in all parameters of germination, shoot length, root length and dry weight of root and shoot due to the treatment with the two different salt sources. Germination percentage, energy, capacity & speed and the seedling growth (shoot length) of the variety gradually decreased with increasing concentration of salt solutions. Germination and the length of root & shoot were negatively related to salt levels.

Influence of Rootstock on cv. Cornalin Behaviour in the Central Valais

The agronomical and oenological behaviour of the Vitis vinifera cv. Cornalin was studied in relation to the choice of the rootstock at the Research station Agroscope Changins-Wädenswil ACW, in Leytron (VS). The following rootstocks were chosen for this trial: 3309 C, 5BB, Fercal, 41B MGt, 101-14 MGt and 161- 49 C. The rootstocks mainly influenced the vigour and the mineral uptake of the graft. 41B MGt and 161-49 C were less vigorous than the other rootstocks. They also had a lower nitrogen and potassium uptake. 41 B presented a high magnesium uptake as well as fewer bunch stem necrosis symptoms whereas 5BB, Fercal and 101-14 MGt had a lower magnesium uptake and more bunch stem necrosis symptoms. The wines issued from the rootstocks 41 B and 161-49 C were slightly more acidic. The rootstock 101-14 MGt appeared to be more sensitive to drought.

Grain Sorghum - an Arable Crop with Attractive Properties, as yet Unknown in Switzerland

With 40.5 million hectares under cultivation, Sorghum bicolor (L.) Moench is the world’s fifth-most important arable crop. Although primarily cultivated in warmer regions, the area devoted to this crop in Europe has increased over the past few years – among other things because sorghum produces attractive yields even when little water is available. In order to increase the sparse information on cultivating grain sorghum currently available in Switzerland, trials were conducted from 2009 to 2011 in various Swiss regions with several varieties. In favourable environmental conditions, the earliest maturing varieties achieved yields of up to 110 dt ha⁻¹ with 16 % humidity at the day of the harvest in small-plot trials. Because of sorghum‘s greater need for warmth than maize, planting in cold-air zones or in basins, or early sowing should be avoided. This will ensure a relatively quick juvenile development and good pollination. A piglet feeding trial showed that Swiss-produced sorghum is of comparable quality to the imported grain, and meets feeding requirements. Preliminary infection trials with Fusarium species resulted in low infection rates and low deoxynivalenol (DON) contents. As evidenced by the successful cultivation of Sorghum bicolor in favourable maize-growing areas of Switzerland, changing climatic conditions make it essential for Swiss farmers to have access to more detailed information of different types of millet and sorghum grown in Switzerland.

Influence of Potassium and Zinc Fertilization on Productivity, Quality, Nutrient Uptake, Morpho-Physiological and Bio-Chemical Parameters of Wheat

A field experiment was conducted at the experimental farm, S.K.N. College of Agriculture, Jobner, Jaipur, Rajasthan during the Rabi season of 2007 and 2008 to study the effect of potassium and Zn fertilization on productivity, quality, nutrient uptake, morpho-physiological and bio-chemical parameters of wheat (Triticum aestivum). Treatments comprised of four levels each of fertilizer potassium (0, 20, 40 and 60 kg K₂O/ha) and Zn (0, 3, 6 and 9 kg Zn/ha) in randomized block design with four replications. Results revealed that the productivity of wheat (grain and straw yield) was increased significantly with application of K and Zn. Indicating the better osmoregulation and adaptive characteristics of plant the morpho-physiological parameters viz., relative leaf water content and transpiration rate of wheat were significantly increased, whereas osmotic potential decreased with the application of K and Zn. Application K and Zn increased significantly the bio-chemical parameters of wheat crop (total phenol, allantoin, proline, lysine, chlorophyll and protein content) indicating the higher produce quality from human and animal nutrition point of view (lysine and protein content) and higher stress resistance in crop against biotic and abiotic stresses (total phenol, allantoin, proline and chlorophyll content). The application of K increased significantly the N, P, K, S and Zn content in grain and straw, whereas the increasing levels of Zn increased N, K, S and Zn content in grain and straw indicting the enhancement in nutritional quality of wheat produce. Due to high nutrient content and higher yield the uptake of nutrients was also higher in the produce. With increase in K and Zn levels Physiological Efficiency and Apparent Recovery of applied K and Zn were decreased while Nutrient Harvest Index was increased up to 60 kg K₂O and 6 kg Zn/ha.

Soil Potassium Fertility and Management Strategies in Andhra Pradesh Agriculture

Declining soil potassium has emerged as an important productivity constraint in Indian agriculture. The K deficiency in soils and crop plants is particularly a serious management issue in red, lateritic, acidic, alluvial and coastal sandy soils. A variety of soils such as red and lateritic followed by black, alluvial, coastal sandy soil occur in different agro-climatic zones of Andhra Pradesh. Present paper examines the potassium supplying characteristics of these soils types in terms of properties contributing to K availability, forms of available K, soil K reserves as determined by step and constant rate K, release kinetics, quantity/intensity parameters, dynamics under long-term intensive cropping, crop response to applied K in irrigated and rainfed conditions. Potassium balance in soil under continuous cropping and the role of nonexchangeable K in crop K needs and its inclusion in soil testing was highlighted. Significant responses to applied K was obtained in both irrigated rice and several rainfed crops like maize, cotton, groundnut, castor, chickpea, sunflower etc. to applied K in the range of 40-80 kg K₂O ha^-1. Crop K requirements and recommendations and future research needs on various aspects of K management in soils of A.P. have been indicated. Large-scale cultivation K exhaustive crops like banana, cotton, maize etc. cannot be supported by K deficient red soils unless sufficient external K application of efficient recycling of crop residue is done.

An Overview of Soil Fertility Management, Maintenance, and Productivity in Kenya

Soil fertility-related issues are a major concern to Kenya. For more than a decade, the country has experienced a declining trend in agricultural production as exemplified by low yields of major crops. Crop yields of no inputs declined by over 70% in 11 years. Continuous cropping without fertilizer caused declines in soil organic carbon and microbial biomass size and activity compared to farmyard manure alone or in combination with inorganic fertilizer. In fertilizer trials throughout the country, nitrogen (N) and phosphorus (P) were deficient in 57% and 26% of the sites, respectively. With declining productivity and soil nutrient depletion, many farmers have taken the initiative to improve the situation by use of both inorganic and organic nutrient sources such as manures, composts and traditional fallows where possible. There is strong evidence that application of fertilizer increases crop production, especially for maize. Among the bio-physical factors, a soil fertility decline remains the single most important constraint to food security in this region. After soil moisture stress, low soil fertility is the most important constraint limiting crop productivity in sub-Saharan Africa.

Productivity and Fertility of Soils in the Indo-Gangetic Plains of South Asia

Fertile soils are a fundamental asset for a sustainable rice–wheat cropping systems followed in 13 Mha in the Indo-Gangetic plains (IGP). Managing practices for the rice–wheat cropping system are changing and in turn influencing soil fertility parameters. In long-term rice–wheat cropping, soil organic carbon content declined only in soils having high initial organic carbon content. Otherwise, soil organic carbon content tends to remain unchanged or increase with continuous cropping and fertilizer/manure applications. Available P content of the soil also increased with P additions through fertilizers or manures. Soil quality deterioration with respect to K supplying power is being largely overlooked. Deficiency of zinc is widespread in the IGP, but with the extensive use of zinc sulfate, it has reduced in some areas. Deficiency of Fe, Mn, and B is also increasing. The western transects of the IGP are more productive not only because radiation decreases and minimum temperature increases from eastern to western IGP but also due to the application of large amounts of fertilizers and availability of assured irrigation in western transects. Since more nutrients are being removed than added through fertilizers, farmers have to apply increasing doses of fertilizers to sustain the productivity levels.

Soil Fertility and Crop Nutrition Research at an International Center in the Mediterranean Region: Achievements and Future Perspective

The Mediterranean climate allows for rainfed cropping in the relatively moist cool period from autumn to late spring/early summer. Drought has a constant influence. Soil fertility was partly maintained by fallowing, nitrogen-fixing plants, and animal manures. Considerable changes have occurred due to land use pressure, i.e. decreasing fallow and increasing crop diversification, irrigation, and chemical inputs, especially chemical fertilizers. Generally, N use has increased about 20-fold, while phosphate has also increased significantly. Due to adequate reserves in the soils, there is a limited potassium fertilizer use. Awareness of the significance of micronutrients has developed. This presentation gives a broad overview of nutrients in relation to soil properties and crops, emphasizing nutrient dynamics in agroecosystems and nutrient use efficiency. Chemical fertilizers have contributed significantly to increasing crop output in the Mediterranean region. Fertilizers and nutrients are considered in the broadest sense, i.e. agricultural production, human and animal health, and the environment. Attention is given to the potential contribution of soil and cropping systems to the emission of greenhouse gasses and how soil management is likely to need to respond to the likelihood of climate change. Projections about future changes related to soil resources of the Mediterranean region are seen in the light of global trends.

Fertility and Soil Productivity of Colombian Soils under Different Soil Management Practices and Several Crops

In the Caribbean, valleys of the Andes, Oriental Plains and Andean region of Columbia, there is a great diversity of soils, soil quality and ways and hazards of soil degradation caused by large variations in parent materials, climatic conditions, biodiversity and the physiographic position of the land. Soil and environmental characteristics, soil use and soil degradation in Columbia are specified. There are also opportunities for increased agricultural production. The high degree of soil diversity provides ecological niches for the successful cultivation of modern crop varieties. Alternative cropping practices are suggested. To promote sustainable effects in Colombian soils, a reduction of and change in soil cultivation practices are proposed. Sugarcane fields planted in Alfisols, Vertisols or Mollisols support production levels of >14 t ha⁻¹ month⁻¹ with high sugar production. In Andean or Caribbean soils, tropical fruit production can be maintained at >40 t ha⁻¹ year⁻¹. Oil palm fruit can reach production levels of 33–35 t ha⁻¹. Combining practices results in an improvement in physical, chemical and biological soil properties, maintaining high production levels in soils of low, medium or high fertility. It is concluded that the productivity of Colombian tropical soils is a function of soil quality and management.

Integrated Nutrient Management for Sustainable Cassava Production in South Western Nigeria

Due to cost, availability and technical reasons, agriculture with high chemical fertilizer input has not been practiced in Nigeria. Animal manures are not available in the required quantities and are often low in one or more of the major nutrients: N, P, and K. This study investigated the effect of an integrated use of organic manures and inorganic fertilizer on cassava production and soil parameters. Single applications of manures and an inorganic fertilizer at recommended rates served as references. Crop responses were highest with integration of manures with no productivity gaps when compared with the rates of single applications of the recommended inorganic fertilizer and manures. Nutrients were made most available when manures were integrated with inorganic fertilizer. Root yield was highest with the integrated use of manures and fertilizer while stem yield was highest with the single applications of manure. Lowest responses were obtained in the control treatment without fertilization for all parameters. Crop and soil productivity can be sustained with the integration of different manures as a viable alternative to the single applications of either manure or inorganic fertilizer.

Application of Potassium and Magnesium on Turmeric (Curcuma longa) to Increase Productivity in Inceptisols

Turmeric (Curcuma longa) is a tropical rhizomatous crop. However, inadequate nutrient management and nutrient mining has led to low productivity of fresh rhizome yield in the major turmeric growing regions in South India. In order to study the effect of potassium and magnesium on turmeric production and on its quality attributes of the crop under conditions of adequate supply of nitrogen and phosphorus, a pot experiment was carried out on the Irugur soil series (Inceptisols) in the western zone of Tamil Nadu. The experimental design was a randomized block design with six treatments: K1 − control (no potash), K2 − (40^a + 4^b), K3 − (80^a + 8^b), K4 − (120^a + 12^b), K5 − (160^a + 16^b), K6 − (200^a + 20^b) (^akg of K₂O ha⁻¹/^bkg of MgSO₄ ha⁻¹) replicated threefold. The treatment (K6) recorded highest tiller count (14 plant⁻¹), rhizome yield (963 g plant⁻¹), and curcumin content (4.28%), which was statistically significant to all other treatments. These results suggest that the turmeric crop grown under intensive cropping systems requires large amounts of potassium and to certain extent requires magnesium for increasing productivity, enhancing quality, and for maintaining nutrient ratios in turmeric crop.

Enhancement of Rice Productivity and Soil Fertility through System Integration of Organic and Mineral Fertilizers in Vertisols

Field experiments were conducted in a Vertisol for two years to study the response of lowland rice to N from organic and mineral fertilizer tested at N equivalence. The treatments consisted of different organic materials as N fertilizer, viz composted coir pith green manure, sugarcane trash compost, vermicompost, poultry manure and farmyard manure (FYM) applied at 100% N and combination of 50% N from above organic materials and 50% N from urea besides 100% N through urea and control. The recommended dose of fertilizer (RDF) was 120:60:60 N, P₂O₅ and K₂O kg ha⁻¹. The results revealed that addition of organics or urea or both enhanced the growth, rice yield and nutrient status over control. The highest grain yield (4.95, 5.33 t ha⁻¹) and straw yield (7.31, 7.73 t ha⁻¹) for the two years were noticed with vermicompost plus urea (50% N each) which was on par with poultry manure plus urea (50% N each). Combined use of organic fertilizer along with mineral N recorded higher concentrations of NH₄-N and NO₃-N in soil and increased total N uptake. Nutrient use efficiency was compared to individual application. It was more in vermicompost- amended soil followed by green manure and poultry manure.

Moisture Conservation and Fertilizer Use for Sustainable Cotton Production in the Sub-Humid Savanna Zones of Nigeria

In the arid and semi-arid regions, soil moisture deficiency largely limits sustainable crop production. In the Nigerian dry Savanna (Northern Guinea savanna, arid and semi-arid zones), dry spells commonly occur between June and July, often lasts beyond three weeks. Rainfall is unevenly distributed and results in insufficient soil moisture for crop production. Soils at the uplands are commonly sandy loam to loamy sand at the surface horizons, have inherently poor fertility status, poor moisture retention capacity and rapidly degrade due to sheet erosion, continuous cultivation and overgrazing. The study on cross banding of ridges to conserve moisture and use of boron in association with nitrogen, and without boron was therefore conducted in Sabon Gari Garu areas in Katsina State, in the dry savanna of Nigeria during the 2007 and 2008 cotton cropping seasons. Data obtained were statistically analyzed. Results show that treatment with tied ridges + NPK + boron (415.70 kg ha⁻¹ and 312.47 kg ha⁻¹ cotton in respective years) resulted in significant higher cotton lint yields in 2007 and 2008 than NPK + boron treatments (245.20 kg ha⁻¹ and 255.16 kg ha⁻¹ cotton in 2007 and 2008, respectively). Cross banding of ridges is recommended for farmers to conserve soil moisture and application of NPK + boron fertilizers.

Changes in Fertilisation and Liming of Soils of the Czech Republic for the Past 20 Years

Some basic soil fertility parameters have been monitored in the Czech Republic since 1961, at intervals of three to six years, as a part of the national agrochemical soil testing programme. This mandatory programme governs the wording of later regulations on fertilisers and covers in particular the determination of soil reaction and content of available nutrients (P, K, Mg and Ca). In specific cases (e.g. application of sewage sludge to soil, soil testing in organic farming, soil damage caused by flooding, etc.), soil physical and microbiological parameters are also measured. The results for the past 20 years (1989–2008) show a decreasing tendency in pH value and content of available nutrients in agricultural soils. The land parcel identification system (LPIS) is used for testing, and all sampling areas are fixed in the national mapping system (S-JTSK). All the results are available to farmers and government bodies.

Potassium Release from Sand, Silt and Clay Fractions in Calcareous Soils of Southern Iran

The release of non-exchangeable potassium from 24 calcareous soils of divergent mineralogy, from southern Iran, was examined. Sand, silt and clay particles were fractionated after dispersion with an ultrasonic probe. Samples were extracted with 0.01 M CaCl₂ for 30 successive 2-h periods. The clay fraction released the largest amount of K in each soil. Cumulative K released ranged from 175 to 723, 35 to 128, and 71 to 146 mg kg⁻¹ contributing 20?90, 4?39 and 2?54% for clay, silt and sand fractions, respectively. The lower proportion of K released from sand and silt fractions can be explained by the presence of a high content of CaCO₃ and quartz in these fractions. The release kinetics for the non-exchangeable K data showed that parabolic diffusion and power function were the best fitting kinetic models. This indicated that slow diffusion of K from the mica interlayer positions is the main rate-controlling process. Cumulative K released and constant b values of parabolic diffusion model correlated significantly with the mica content of the clay fraction.

No-Till and Strip-Till Corn Production with Broadcast and Subsurface-Band Phosphorus and Potassium

Fertilizer placement is often designed to improve nutrient availability. Our objective was to determine the effect of P and K rate and placement in no-till and strip-till on grain yield; water, P, and K values in the soil; and the distribution of corn (Zea mays L.) roots. A 4-yr field experiment was setup near Urbana, IL, with a corn–soybean [Glycine max (L.) Merr.] rotation. Tillage/fertilizer placement was the main plot [no-till/broadcast (NTBC), no-till/deep band (NTDB), and strip-till/deep band (STDB)]; deep band was 15-cm beneath the crop row. Phosphorus fertilizer rate (0, 12, 24, and 36 kg P ha⁻¹ yr⁻¹) was the subplot, and K-fertilizer rate (0, 42, 84, and 168 kg K ha⁻¹ yr⁻¹) was the sub-subplot. Measurements included grain yield and yield components, grain and shoot P and K concentrations, root parameters, and soil-water, P, and K values. Strip-till/deep band produced greater kernels row⁻¹ and 9.43 Mg ha⁻¹ yield that was 7.8% greater than NTBC and 7.9% greater than NTDB. Deep banding increased soil P and K test values beneath the crop row and lowered soil surface test values compared with broadcast applications, but had no effect on root distribution. Across treatments, greatest apparent P and K uptake occurred in the surface layer where most roots were present and where precipitation replenished water to a greater extent than deeper layers. Relative to NTBC, STDB had 24% greater apparent-P and 23% greater apparent-K uptake rates. The results indicate that improved conditions for nutrient uptake provide a competitive advantage for production with STDB relative to no-till treatments.

The Effects of Chloride and Potassium Nutrition on Seed Yield of Annual Canarygrass

The year-to-year variability of seed yield in annual canarygrass (Phalaris canariensis L.) is a major concern among growers. A field experiment was conducted at 13 site-years across Saskatchewan to determine the response of annual canarygrass seed yield to K and Cl, and to provide better recommendations to producers on the use of KCl fertilizer in annual canarygrass based on soil test results. Potassium did not affect the yield or development of annual canarygrass over a range of 155 to 717 kg K ha⁻¹ in the top 15 cm of soil. Chloride had a large impact on annual canarygrass seed yield; seed yield increased by approximately 24% when Cl was added in the form of KCl or CaCl₂ when averaged across all sites. The seed yield increased because the application of Cl increased panicle size (seeds panicle⁻¹). The magnitude of the response tended to increase as level of Cl in the soil decreased. Annual canarygrass growers need to measure Cl when using soil tests to determine fertilizer requirements. It is recommended that 9.1 kg Cl ha⁻¹ in the form of 20 kg ha⁻¹ of KCl be applied when the Cl level in the surface soil (0–15 cm) is below 70 kg Cl ha⁻¹. The findings encourage growers to conduct individual field test strips to determine the strength of the Cl response.

Soybean Yield and Chemical Composition in Response to Phosphorus-Potassium Nutrition in Kashmir

Soybean [Glycine max (L.) Merr.] has increasing nutritional, commercial, and economical value, and P and K nutrition may be needed to increase yield and profit. A 2-yr (2008–2009) field experiment with rainfed soybean was conducted in the hilly region of the state of Azad Jammu and Kashmir (AJK), at Rawalakot, Pakistan. The aim of the study was to evaluate the effects of P–K fertilization on soybean root nodulation, seed yield, seed composition and N, P, and K uptake. The experiment was conducted in a randomized complete block design with three replications. Treatments included three levels of P (60, 90, and 120 kg P₂O₅ ha⁻¹), two levels of K (40 and 80 kg K₂O ha⁻¹), and a control, represented as P₀, P₆₀, P₉₀, P₁₂₀ and K₀, K₄₀, and K₈₀, respectively. Results indicated that number of root nodules increased with P–K fertilization to 75 and 136 compared with 68 in the control. Yield responses to P–K fertilization occurred to all rates, and the highest yield was observed in the combined treatment of P₁₂₀K₄₀. Total N, P, and K uptake in the plant (shoot + seed) tended to follow yield responses, while seed protein was increased by 8 to 13% due to P and 11 to 19% due to K. Application of P or K alone or in combination significantly increased oil content. This study demonstrates that P- and K-deficient soils are likely to produce crops with low yields and low seed oil levels, and appropriate P–K management could be an effective approach to increase and sustain soybean production in the mountain ecosystems.

Yield and Potassium Balance in a Wheat-Maize Cropping System of the North China Plain

This study examined the effects of long-term K fertilization on crop yields and K use efficiency and balance under a wheat (Triticum aestivum L.)–maize (Zea mays L.) cropping system in the Fluvo-Aquic soil of Yucheng Comprehensive Experiment Station in the North China Plain (NCP). Results showed that the native K supply could maintain annual grain yields at stable levels at 10.7 Mg ha⁻¹ for >19 yr with applications of N and P alone. The application of K alone significantly improved maize yield by 46% but wheat showed no response. The agronomic efficiency, physiological efficiency, and partial factor productivity but not apparent use efficiency of wheat were significantly lower than the average values previously reported. In addition, only 43% of K found in the aboveground biomass of wheat and maize came from an annual application of fertilizer. The application of K caused a large K surplus, even with balanced fertilization, in which 33% of applied K was left in the soil, mostly in the 0- to 20-cm depth due to its surface application. The data indicated that the native K supply in the NCP might sustain normal wheat yields for about 10 to 30 yr. Generally, in a Fluvo-Aquic soil with a high content of soil available K, soil K can be used. In this study, 471 kg ha⁻¹ yr⁻¹ K input was excessive for the growth of maize and wheat, and at least 120 to 150 kg ha⁻¹ yr⁻¹ K could be saved with the use of balanced fertilization.

Alfalfa Nitrogen Credit to First-Year Corn: Potassium, Regrowth, and Tillage Timing Effects

Compared with corn (Zea mays L.) following corn, N guidelines for first-year corn following alfalfa (Medicago sativa L.) in the U.S. Corn Belt suggest that N rates can be reduced by about 168 kg N ha⁻¹ when ≥43 or 53 alfalfa plants m⁻² are present at termination. These guidelines have been questioned by practitioners, however, as corn grain yields have increased. We conducted experiments at 16 locations in Minnesota to address questions regarding N availability to first-year corn after alfalfa relating to the effect of carryover fertilizer K from alfalfa and the amount and timing of alfalfa regrowth incorporation. Corn grain yield, silage yield, and fertilizer N uptake were not affected by carryover K or amount or timing of regrowth incorporation. Maximum corn grain yield ranged from 12.0 to 16.1 Mg ha⁻¹ among locations but responded to fertilizer N at only one. At that location, which had inadequate soil drainage, the economically optimum N rate (EONR) was 85 kg N ha⁻¹, assuming prices of US$0.87 kg⁻¹ N and US$132 Mg⁻¹ grain. The EONR for silage yield across 6 of 15 locations where it was measured was 40 kg N ha⁻¹, assuming US$39 Mg⁻¹ silage. These results demonstrate that on highly productive medium- to fine-textured soils in the Upper Midwest with ≥43 alfalfa plants m⁻² at termination, first-year corn grain yield is often maximized without fertilizer N, regardless of alfalfa regrowth management or timing of incorporation, but that small N applications may be needed to optimize silage yield.

How Different Long-Term Fertilization Strategies Influence Crop Yield and Soil Properties in a Maize Field in the North China Plain

The impact of fertilization on maize (Zea mays L.) yield and soil properties was investigated in a long-term (> 18 y) experimental field in N China. A completely randomized block design with seven fertilizer treatments and four replications was used. The seven fertilizer treatments were (1) compost (COMP), (2) half compost plus half chemical fertilizer (COMP1/2), (3) balanced NPK fertilizer (NPK), (4–6) unbalanced chemical fertilizers without one of the major elements (NP, PK, and NK), and (7) an unamended control (CK). In addition to maize yield, soil chemical and biological properties were investigated. Compared to the balanced NPK treatment, maize yield from the COMP treatment was 7.9% higher, from the COMP1/2 was similar, but from the NP, PK, NK, and CK treatment were 12.4%, 59.9%, 78.6%, and 75.7% lower. Across the growing season, microbial biomass C and N contents, basal soil respiration, and fluorescein diacetate hydrolysis, dehydrogenase, urease, and invertase activities in the COMP and COMP1/2 treatments were 7%–203% higher than the NPK treatment. Values from all other treatments were up to 60% lower than the NPK treatment. Maize yield is closely related to the soil organic C (OC) and biological properties, and the OC is closely related to various biological properties, indicating that OC is a suitable indicator for soil quality. Our results suggest the most limiting nutrient for improving the yield or soil quality was P, followed by N and K, and balanced fertilization is important in maintaining high crop yield and soil quality. Additionally, increases in OC, N, and biological activities in COMP and COMP1/2 treatments imply that organic compost is superior to the chemical fertilizers tested.

Potassium Use Efficiency of Maize Hybrids

Maize hybrids exhibit better potassium use efficiency (KUE) and utilize soil N in an efficient way, thus reduce input cost and conserve environment. For the screening of hybrids with proper dose of K, experiment were laid out in randomized complete block design with split plot arrangement, randomizing maize hybrids in main plots (H₁= Pioneer-3012, H₂=Pioneer-3062, H₃=Pioneer-30D55) and K application levels (K₀=0, K₁=100, K₂=150, K₃=200 and K₄=250 Kg ha^-1) in subplots with four replications. It was observed that Pioneer-30D55 significantly gave higher KUE (1.94) than Pioneer-3012 (1.86), yet it was at par with Pioneer-3062 (1.92). K application at all levels significantly increased KUE over control. All K levels except control produced statistically similar KUE. As far as N present in soil after harvest, Pioneer-30D55, probably due to its efficient root system left minimum N (0.042 %) in the soil and significantly differed with Pioneer-3062 (0.043%) and Pioneer-3012 (0.044%), which also significantly differed with each other. Minimum N %age left in soil after crop harvest (0.046) was observed, when 200 kg K ha^-1 was applied which significantly differed with N %age left in soil after harvest crop (0.045) obtained when 250 kg K ha^-1 was applied, where as maximum N %age left in soil after harvest (0.042) was recorded in control. It was therefore concluded that Pioneer-30D55 was the most efficient hybrid

DOC Trial: Nutrient Supply in Winter Wheat - Where is the Deficit?

The nutrient supply of winter wheat was one of the topics investigated by the DOC long-term system comparison from 1978 to 2003. The aim of this trial is to provide evidence of nutrient-related yield limitations in organic farming systems. Substantial differences in yield between «organic» and «conventional» farming systems and different fertilisation intensities were primarily attributed to the delivery of nutrients - in particular, nitrogen - to the plants. Because the soil phosphorus supply was adequate in all DOC systems over the entire trial period, phosphorus was ruled out as a co-limiting factor. The plant analyses of straw and grain exhibited high figures and a low differentiation for phosphorus, thus confirming the soil findings. By contrast, potassium was identified along with nitrogen as a co-limiting factor in the organic systems at the low fertilisation intensity and in the unfertilized control. This was indicated by the differentiation of potassium content in the above-ground biomass and the available soil potassium content. Despite this, both the biodynamic and bio-organic system exhibited a balanced potassium supply at the high fertilisation intensity. Both bio-systems may therefore be considered sustainable at this fertilisation intensity.

Fertiliser Research - Some Unanswered Questions

Expansion in the area of soil fertility and fertilizer research has resulted in the generation and publication of voluminous amount of information. While this is a welcome development, there are cases where data generation has over taken data interpretation and its in house quality assessment. This has resulted in wide gaps in our information in terms of unanswered questions as also some hard to explain results reported. This paper raises some issues, giving specific examples from published research, to highlight the fact that while a lot progress has been and is being made, any vital questions remain unanswered. This is primarily because many research projects follow a pre-set protocol of the line of work with insufficient provision to take an investigation to its logical conclusion. Another reason is adoption of short cuts by bypassing accepted research procedures for commercial gains from new products. Unanswered questions reduce the scientific and well as practical applicability of the findings of fertilizer research. This problem can be rectified at the level of researchers and also by the directors of research.

Effect of Nitrogen and Potassium Nutrition in Pomegranate Grown in Laterite Soil

To find out the nitrogen and potassium requirements in pomegranate cv. Ruby grown in laterite soil of West Bengal, an investigation was carried out for three consecutive years which started when the plant age was 5 years. Results indicated that growth of the plants was not so much affected due to different doses of nitrogen and potassium. But fruit yield and weight of the fruit were significantly and constantly improved with the yearly application of 300 g each of nitrogen and potassium per plant. Fruit quality in respect of juice content, T.S.S. and sugar was not appreciably increased due to nitrogen and potassium nutrition, however, Vitamin-C content, on the other hand, was significantly greater with the application of 300 g of nitrogen and 200 g of potassium per plant per year.

Long-Term Effects of Nutrient Management on Soil Health and Crop Productivity Under Rice-Wheat Cropping System

An ongoing long-term experiment under rice-wheat cropping was selected to investigate the effect of organic and fertilization on the sustainability of rice-wheat system. Application of fertilisers along with organic manures (FYM, press mud and green manure) produced significantly higher grain yield of rice compared to application of fertilizer alone. Green manuring with Sesbania aculeata before rice transplanting almost saved 50% of NPK fertilisers. The grain yield of rice and wheat decreased significantly with time in control and with imbalanced application of NPK fetilisers. The decrease in rice yield amounted to 0.055 to 0.134 Mg ha^-1 yr^-1 and in wheat yield from 0.038 to 0.116 Mg ha^-1 yr^-1. The data on soil fertility parameters suggested that the gradual decline in soil organic matter and available Zn content of the soil were the major factors contributed towards this yield decline. Balanced application of NPKZn fertilsers with and without organic amendments either increased or maintained the sustainability of the rice-wheat cropping system. Thirteen years of rice-wheat cropping system without any fertilisers or organic amendments had deleterious effects on soil health resulting in significant decrease in organic C, available N, P, K and DTPA-extractable micronutrients. However, soil health with respect to contents of organic carbon, available N, P, K, Zn, Cu, Fe and Mn was either maintained or improved significantly with the balanced application of NPKZn alone or in combination with organic manures. Continuous application of FYM, press mud and green manure for thirteen years sequestered 14.5, 15.8 and 5.3% of the added carbon in soil, respectively. Integrated use of fertilisers with organic manures led to marked increase in the contents of various pools/forms of organic carbon and nitrogen and resulted in redistribution of micronutrient contents from non-available forms (carbonate and crystalline iron oxides) to readily available (water-soluble plus exchangeable) and potentially available (organic fraction and manganese oxides and amorphous iron oxides) forms in soil.

Soil Fertility Management Strategies for Maximising Cotton Production of India

Cotton is the most important commercial fibre crop in our country. The Bt transgenic hybrids introduced for cultivation in 2002, now occupies more than 90% of the cotton area. Although, it contributed significantly to productivity and production increases, average productivity levels are still lower than the world average. Poor soil fertility is one major constraint in achieving potential yield levels. A deficiency of at least a single nutrient (N) is most common and in most of the cases it is a multiple nutrient (N, P, K, secondary nutrients – S and micronutrients – Zn, B) deficiency. The results from vast experiments conducted on the Asiatic and Upland cotton cultivars and the hybrid cultivars, indicate it is not sustainable to rely on single nutrients. Among the nutrient management options, balanced fertilization and site-specific nutrient management (SSNM) approaches have been found to be suitable alternatives. However, very little is known about the latter especially for the Bt transgenic hybrids. Significant response to the application of micronutrients has been reported and the cost benefit ratio is highly favourable. Application of organics along with the fertilisers not only enhanced yields but also improved yield stability in the long-term. The main constraint is the availability of adequate quantities of organic sources of plant nutrients. Most of the cotton growing fields in the states of Maharashtra, Andhra Pradesh, Gujarat, Punjab and other northern regions, Tamil Nadu, Karnataka etc. have multi-nutrient deficiency and more attention is required for better nutrient management practices as cotton is one of the most nutrient exhaustive crops. Target yields of Bt cotton were achieved in tune with the application nutrients up to a target yield of 3.0 t/ha (165:75:120:20:20 kg/ha NPK+ ZnSO₄+ FeSO₄), while yield of 3.5 t/ha was possible in treatment applied with nutrients for a target yield of 4.0 t/ha (220:100:110:25:25 kg/ha NPK+ ZnSO₄+ FeSO₄) at Dharwad on Vertisols. The cotton responds to application of K @ 120 kg/ha in calcareous soils of Saurashtra. Response to B application in light textured and highly percolated as well as calcareous soils of North Gujarat and Saurashtra regions is reported. Large numbers of on-farm evaluation farmer participatory SSNM and Integrated Nutrient Management (INM) trials in major cotton growing districts of Andhra Pradesh (Warangal, Khammam, Nalgonda and Adilabad), Gujarat (Anand), Punjab, Karnataka, Maharashtra, Tamil Nadu etc. indicate the substantial improvement of cotton yields due to addition of deficient nutrient in soils. Cotton grown in light textured red soils showed moderate to severe magnesium deficiency which resulted in reduction of boll number and poor plant growth. BC ratio of better nutrient management was recorded up to 4 in some of the field demonstrations. Foliar spray of nutrients also showed significant economic benefits. Small dose of nitrogen after intermitted droughts also benefited the cotton in improving foliage and boll size. Application tank silt (40-60 t/ha) in light textured red soils and addition of FYM/compost resulted in the better tolerance of cotton to intermittent droughts and prolonged wilting of foliage due to water stress during drought spells.

Measures to Sustain and Restore Declined Productivity in Alfisols under Long-Term Fertiliser Experiments

Acid soils (Alfisols) covers sizeable areas in the states of Kerala in South, Assam, Arunachal, Meghalaya in North East, Uttaranchal and Himachal Pradesh in North and Chhattisgarh, Jharkhand and Orissa in East. Nearly 25-30 mha cultivable land having pH less than 5.5 is associated with several inherent problems like inadequacy of P, K, Ca, Mg and B and toxicity of Cu, Al and Fe. Soil acidity and poor fertility have very strong positive relationship. Long-term fertilizer experiments played a vital role to enhance and sustain the productivity of these soils. In Alfisols, use of nitrogenous fertilizer without ensuring supply or availability of other nutrients in right proportion and soil amendments hat detrimental effect on productivity and soil health. At Palambur application of P enhanced the average crops productivity by 16.8 in maize and 12.1 q ha^-1 in wheat and application of K resulted increase in productivity of maize by 29.4 and wheat by 18.7 q ha^-1. At Palampur, S is another nutrient which increased the crop productivity significantly. Application of soil amendments like lime and FYM coupled with recommended doses of N, P, K and S increased the yield to the extend of 9.0 and 5.8 q ha^-1 in and 14.3 and 8.29 q ha^-1 in maize and wheat respectively. A similar effect of lime and FYM was also recorded at Bangalore and Ranchi. Thus, balanced application of nutrients coupled with soil amendments ensured increase in productivity approximately by 1.5 to 2.0 t ha^-1 annually which could give predictably additional production of 40 to 50 mt grain annually. The superimposition of nutrients (P, K and FYM) in N plots which are degraded due to continuous application of N alone for 32 years proved that these plots can be rejuvenated within a period of 2-3 years.