Mineral nutrition of slash pine in subtropical australia. I. stand growth response to fertilization

Fertilization at plantation establishment and later age is often required to maximize stand growth of slash pine (Pinus elliottii) in subtropical Australia. A field experiment was conducted to examine stand growth response of slash pine in the first 11.5 years of plantation following (1) initial fertilization at plantation establishment with phosphorus (P) at 11, 22, 45 and 90 kg P ha^–1 which were either banded or broadcast in the presence or absence of basal fertilizers containing 50 kg nitrogen (N) ha^–1, 50 kg potassium (K) ha^–1 and 5 kg copper (Cu) ha^–1 and (2) additional application of 40 kg P ha^–1 at age 10 years.The initial P fertilization significantly increased the stand growth in the first 9.6 years. The P banded application was more effective in improving the stand growth than the P broadcast application. Application of the N, K and Cu basal fertilizers did not affect the stand growth. Overall, 53–73% of the variation in basal area and volume growth in the first 9.6 years was explained by the initial P fertilization, indicating that P deficiency was the major factor limiting the stand growth under the experimental conditions. Optimum plantation age, at which the maximum periodical annual increment (PAI) of basal area was obtained, increased from age 10.9 to 12 years when the initial P rate increased from 11 to 90 kg P ha^–1. Application of additional 40 kg P ha^–1 at age 10 years resulted in a further improvement in the stand growth at age 11.5 years. With 66% of the variation in basal area PAI between ages 9.6 and 11.5 years, 50% was explained by the initial P fertilization and 16% by the additional P applied at age 10 years. Similarly, 51% and 12% of the variation in volume PAI were attributed to the initial P fertilization and the additional P application, respectively. This highlights the need of refertilization with P on some established stands of slash pine at later ages.     

Mineral nutrition of slash pine in subtropical Australia. III. Relationships between foliar P concentration and stand growth

Foliar P concentration of slash pine was significantly related to the stand growth in the first 11.5 years. The relationship between foliar P concentration and total stand growth at foliar sampling improved as the plantation aged with coefficient of determination (R²) increasing from 0.14–0.15 at age 3.3 years to 0.56–0.65 at age 9.6 years. However, only 12–18% of the variation in total stand growth was explained by foliar P concentration at age 11.5 years when additional 40 kg P ha^–1 was applied to the stands at age 10 years. This suggests that caution should be exercised in interpreting the foliar P concentrations of the established stands which had received application of P fertilizer just prior to foliar sampling. Periodic stand growth was more closely related to the foliar P concentration than total stand growth. Basal area and volume periodic annual increment (PAI) was better related to the foliar P concentration than height PAI.Optimum foliar P concentration, at which the maximum stand growth was obtained, was between 0.093% and 0.110%. The optimum foliar P concentration for height PAI immediately prior to foliar sampling decreased from 0.097% at age 3.3 years to 0.070% at age 9.6 years. Critical foliar P concentration at age 9.6 years, at which 90% of the maximum basal area growth was obtained, was between 0.066% and 0.070%. Both optimum and critical foliar P concentration might decrease as the plantation aged.     

Effect of long-term fertilization on the biomass production and nutrient status of Scots pine stands

The effect of repeated fertilization on soil properties, nutrient status of the stand and the biomass production of the above-ground components of the trees are examined in the study on the basis of material from three fertilization experiments. Two of the experiments were established in sapling stands, and the third in a pole-stage stand. The stands had received repeated doses of fertilizer totalling N 597–776 kg ha^–1 and P 69–80 kg ha^–1 over a 26 to 30-year study period in accordance with a factorial experimental design.Nitrogen fertilization increased the amount of organic matter in the humus layer of two of the experiments by 25–35%, and the amount of total nitrogen by about 50%. The C/N ratio of the humus layer in all three experiments decreased as a result of nitrogen fertilization by 11–18%. No decrease in soil pH was detected.At the end of the experimental period, i.e. 5–6 years after the most recent fertilization, the nitrogen concentration of the current needles on the nitrogen-fertilized plots was clearly lower than that of the older needle age classes. Fertilization did not have any marked effect on the concentrations of other macronutrients in the needles.Of the above-ground components, stemwood production was affected the most by nitrogen fertilization. The range of the relative growth response was 22–36%. The effect on branch biomass was 25% on the least fertile site, but there was no effect on the most fertile site. The effect of nitrogen fertilization on the needle biomass component was least, from –8 to 18%, owing to the 5 to 6-year time lag between the preceding fertilization and biomass sampling. A negative response was found on the least fertile site, where six years had elapsed since the most recent fertilization. However, on this site the proportion of over one-year-old needles was greater on the nitrogen-fertilized plots (24%) than on the others (19%). Phosphorus fertilization had only a slight effect on stemwood production.In general, nitrogen fertilization decreased the crown biomass per unit volume of stemwood.     

超级杂交稻营养套餐施肥技术示范试验报告

介绍超级杂交水稻应用营养套餐施肥技术和示范试验结果,667 m2产量达到867.17 kg,比常规施肥对照区增产34.41%。主要增产因素是施用了高效优化的高科技肥料——含硅、锌养分的腐植酸复合肥和高效叶面肥,充分满足了水稻超高产栽培的营养需求。     

Mineral nutrition and fertilizer response of grain sorghum in India — A review over the last 25 years

Researches on the mineral nutrition and fertilizer response of grain sorghum (Sorghum bicolor (L) Moench) carried out during the last 25 years in India are reviewed here. In general, N,P,K, Fe and Mn concentrations in vegetative plant parts decreased with crop age, while the concentrations of Ca, Mg and Cu increased. The concentration of N and P increased in panicle or grains of sorghum with advance in crop age. The seasonal change for other nutrients has not, however, been studied.Accumulation and uptake of N,P, and K by grain sorghum were characterized. Usually N and P accumulated slowly compared with the rapid accumulation of K in early crop growth stage and vice-versa in later stages of growth. As against the sizable mass of N and P into panicle, K was partitioned into stalk.Fertilizer responses to N and P were observed throughout India. Improved varieties and hybrids of sorghum responded to N rates ranging from 60 to 150 kg N ha^–1, whereas a response to P application was observed up to 40 kg P ha^–1. Although responses to K application had been inconsistent, an increase in grain yield of sorghum was observed due to 33 kg K ha^–1. A balanced fertilizer schedule consisting of 120 kg N ha^–1, 26 kg P ha^–1, 33 kg K ha^–1 and 15–25 kg Zn50₄ ha^–1 is recommended for improved productivity of grain sorghum.It is concluded that systematic research efforts should be directed so as to identify problem soils showing deficiencies and toxicities of different nutrients. Characterization of the seasonal changes in the concentration and uptake of different nutrients and determination of critical concentration and hidden hunger of different nutrients in plant tissues would lead to the recommendation of balanced fertilization for different sorghum-growing regions in India.A part of the paper presented in the Silver Jubliee Conference of Indian Society of Agronomy held at H.A.U., Hissar (India) in March, 1981     

Short-and long-term fertility trials in Colombia to determine the nutrient requirements of cassava

One-year simple NPK trials were conducted in 22 locations in four regions of Colombia to determine the response of cassava (Manihot esculenta Crantz) to N, P and K and to relate this response to the available P and K contents of the soil, as well as to the N, P, and K concentrations in youngest fully expanded leaf (YFEL) blades sampled at 3–5 months after planting. It was found that cassava responded mainly to P applications in the low-P soils of the Eastern Plains and of Cauca Department, to K applications only in the Eastern Plains and to N applications principally in the sandy, low-OM soils of the Atlantic Coast. By relating the relative response to P and K to the available P and exchangeable K content of the soil, respectively, critical levels of 4 mg P/kg and 0.17 me K/100 g (both extracted with Bray II) were determined. Similarly, critical levels of 5.6% N, 0.41% P and 1.42% K were determined in YFEL-blades.A long-term fertilizer trial with 35 treatments was conducted for 8 consecutive years in the highly acid low-fertility soil at CIAT-Quilichao, to determine the effect of cassava production and fertilization on soil fertility. Although the first year response was mainly to P and N, already in the second year K became the most limiting nutrient and the importance of K fertilization increased over the years. This trial, and similar long-term fertility trials conducted in Colombia and in various parts of Asia, have all shown the importance of adequate annual applications of K for maintaining high yields of continuously grown cassava.     

Yield and leaf composition of sunflower in relation to N,P, K,and lime treatments

Sunflower (Helianthus annus L), a drought resistant crop, is cultivated widely throughout the world. Still, few studies on the fertility requirements of the crop have been published, particularly in relation to cultivation on highly weathered soils and in terms of using foliar analysis as a tool in diagnosing nutritional needs.Two 3⁴ (N, P, K, lime) factorial experiments (high and low fertility levels) with trace elements as split plots were conducted on Farningham clay loam, a Typic Haplorthox. No significant yield response to added N or micronutrients was found on either experiment. Liming and P fertilization increased seed yields in the low fertility experiment. Increased K application gave significant yield increases in both experiments.Preliminary foliar diagnostic norms were developed using the Diagnosis and Reccommendation Integrated System (DRIS). The prognostic value of these norms was tested using the low fertility experiment. In 32 of the 37 cases where the DRIS analysis could be checked against actual experimental yield results, application of the nutrient diagnosed as the most yield limiting resulted in a positive yield response. These data suggest that sunflowers can be a successful crop on Oxisols provided fertility is adequate.     

Open-circuit-potentials of gas/electrode/YSZ boundary versus molten carbonate reference electrode at medium temperatures: II. Potential response of Au, Pt and Ni-cermet electrodes in CH4 + O2 and H2 + O2 gas mixtures

Values of open-circuit-potentials (OCP) have been determined for pairs of electrodes: Au and Pt, Ni-Ce_0.8Sm_0.2O_1.9 cermet and Au, Pt and Sm_0.5Sr_0.5CoO₃ composite at the YSZ electrolyte, in the uniform atmospheres of xCH₄ + yO₂ + (1 − x − y)Ar gas mixtures with variable x and y coefficients, at 600 °C. The determined dependencies of OCP values on the initial gas mixture compositions have been compared with the respective dependencies calculated for equilibrium or quasi-equilibrium compositions of these gas mixtures. The OCP values for the pair of Pt and Au electrodes have been measured also in the xH₂ + yO₂ + (1 − x − y)Ar uniform gas mixtures but no distinct difference of the OCP values has been observed in this atmosphere. For some pairs of electrodes investigated in xCH₄ + yO₂ + (1 − x − y)Ar atmospheres the measured OCP values have shown differences up to ca 0.9-1.0 V. These differences were stable within large range of compositions of this gas mixture. Within this gas composition range one of the electrodes conserves the potential of oxygen electrode determined by oxygen partial pressure in the initial gas mixture and is insensitive to reaction occurring in the gas phase. These results are discussed on the basis of equilibria or some quasi-equilibria, that establish in the C-H-O gas mixture and the solid carbon deposition is considered. For a given pair of dissimilar electrodes, their selective sensibility to the electrochemical process of oxygen electrode has been confirmed. Within large range of gas mixture concentrations, in the Pt-Au electrode pair Au has shown behavior of the oxygen electrode, whereas the OCP values of the Pt electrode are within the range of hydrogen electrode, also at gas compositions corresponding to the solid carbon stability. With this pair the OCP differences of ca. 600 mV have been obtained. Among three electrodes studied the cermet Ni-Ce_0.8Sm_0.2O_1.9 electrode shows the best electrocatalytic properties resulting in the OCP values following exactly the respective equilibrium dependence. In the pair Ni-Ce_0.8Sm_0.2O_1.9 and Au a stable potential difference of ca. 900 mV have been established. Unexpectedly, Pt electrode in the pair with the Sm_0.5Sr_0.5CoO₃ composite electrode plays role of the oxygen electrode quite insensitive to other components of the equilibrated initial gas mixture. This surprising fact seems indicate that in conditions of the experiments performed the electrocatalytic behavior of the electrode depends not only of the material of this electrode but also on the properties of the second electrode in the given pairs of electrodes.