Effectiveness of Panda Hills phosphate rock compacted with triple superphosphate as source of phosphorus for rape,wheat, maize,and soybean

Abstract

Greenhouse experiments were conducted to evaluate the agronomic effectiveness of Panda Hills phosphate rock (PPR) from southwest Tanzania, its mixture with triple superphosphate (TSP), and a compacted mixture of Panda PR and TSP (PPR+TSP) for wheat, rape, maize, and soybean on two United States soils (Hiwassee and Windthorst). The mixture of Panda PR and TSP was prepared by mixing ground TSP with Panda PR in proportions such that 50% of the total phosphorus (P) in the final mixture was from TSP. The compacted product (PPR+TSP) was prepared by compacting some of the blended mixture of Panda PR and TSP into pellets using a laboratory scale Carver press followed by crushing and screening. The P rates applied to Hiwassee soil were 0, 25, 50, and 100 mg P kg^‐1 for each P source and test crop while on Windthorst soil only one rate of application (50 mg P kg^‐1) was applied to one test crop (rape). A lime treatment was also included on the Windthorst soil to enable evaluation of rape response to the different P sources under calcareous conditions. Wheat and rape were allowed to grow to maturity while maize and soybean were grown for six weeks only. The performance of the P sources as reflected by yield, P uptake and relative agronomic effectiveness (RAE) followed the order TSP>>(PPR+TSP)>(PPR)+(TSP)>>PPR for wheat, rape, maize, and soybean on Hiwassee soil. Panda PR was very ineffective in increasing grain or dry‐matter yields of the test crops on this soil. The mixture of Panda PR and TSP as well as the compacted product increased wheat, maize, and soybean yields and P uptake significantly. The increases in yields were, however, largely attributed to the TSP component of the (PPR)+(TSP) mixture or its compacted product with little or no contribution from PPR. On the alkaline Windthorst soil, the performance of the P sources as reflected by rapeseed yield and RAE followed the order TSP= (PPR+TSP)>(PPR)+(TSP)>PPR. Remarkably compacted PPR and TSP was at par with TSP while PPR alone was 50% as effective as TSP in increasing rapeseed yield. Addition of lime drastically reduced the effective‐ness of Panda PR, but it had little or no effect on the agronomic effectiveness of the (PPR)+(TSP) mixture or its compacted product.     

Low efficiency of Zn uptake and translocation in plants provide poor micronutrient enrichment in rice and soybean grains

Abstract

Recent research has shown the need for an in-depth knowledge of zinc biofortification of cereal and oilseed grains due to its importance to human nutrition. However, little is known about the Zn dynamics in plant–soil system. In this work, we evaluated the effect of soil-applied Zn on the absorption, translocation, and compartmentalization of Zn in rice (Oryza sativa L.) and soybean (Glycine max L. Merrill) plants. The soil used in the greenhouse experiment was fertilized with zinc chloride (ZnCl₂) at rates of 0, 1, 2, 4, and 8?mg Zn kg^?1. The source of Zn was labeled by ⁶⁵Zn with specific activity of 185.5 kBq mg^?1 Zn. The amount of Zn derived from fertilizer and its use in each plants compartment was determined by direct method in isotopic calculations. Rice and soybean plants presented low efficiency in the absorption from soil-applied Zn. The accumulated Zn in the panicle, pod, and grains was not modified, due to its low translocation in the plant. The Zn uptake in rice plants was from 1.34 to 4.60?mg pot^?1 in shoots and just 0.81 to 1.43?mg pot^?1 translocated to panicles. Soybean plants presented Zn uptake between 2.36 and 4.68?mg pot^?1 in shoots, out of which 0.19 to 0.34?mg.pot^?1 and 0.48 to 0.57?mg pot^?1 translocated to grains and pods, respectively. The nutrient utilization from fertilizer was low, with mean values of 12 and 8.7% for rice and soybean plants, respectively. Soil-applied Zn showed low capacity for enriching rice panicle and soybean pod or grain probably due low Zn uptake and translocation.     

Rice Yields Enhanced through Integrated Management of Cover Crops and Phosphate Rock in Phosphorus‐deficient Ultisols in West Africa

The relatively low solubility and availability of phosphorus (P) from indigenous phosphate rock could be enhanced by legumes in the acid soils of humid forest agroecosystems. Crotalaria micans L. was grown in a screenhouse without P or with P from triple superphosphate (TSP) and Malian Tilemsi Rock P. The P response of 20 cover crops was field‐evaluated using TSP and Rock P. In both experiments, the fertilized cover crops were followed by upland rice without mineral N or P application. Mean rice grain yield and agronomic residual P‐use efficiency were similar for both P sources. In the field, 1‐year fallow treatment of Canavalia ensiformis (velvet bean) supplied with Mali Rock P gave the highest rice grain yield of 3.1 Mg ha^?1, more than 180% that of 2‐year continuous unfertilized rice (cv. ‘WAB 56‐50’). Among continuous rice plots, ‘NERICA 2’ (interspecific rice) supplied with Rock P produced the highest yield (2.0 Mg ha^?1), suggesting that ‘NERICA 2’ might have greater potential to solubilize rock P. Results indicate that when combined with an appropriate legume, indigenous rock‐P can release sufficient P to meet the P requirement of the legume and a following upland rice crop in rotation.     

Phosphorus Nutrition of Upland Rice,Dry Bean,Soybean, and Corn Grown on an Oxisol

Rice, dry bean, corn, and soybean are important food crops. Phosphorus (P) deficiency is one of the most yield-limiting factors for these crops grown on highly weathered Brazilian Oxisols. Four greenhouse experiments were conducted to determine P requirements of these four crops. The P levels used were 0, 50, 100, 200, and 400 mg kg^?1. Growth, yield, and yield components evaluated of four crop species were significantly increased with the application of P fertilization. Most of the responses were quadratic in fashion when the P was applied in the range of 0 to 400 mg kg^?1. Maximum grain yield of upland rice was obtained with the application of 238 mg P kg^?1 of soil, maximum dry bean grain yield was obtained with the application of 227 mg P kg^?1 of soil, and maximum grain yield of soybean was obtained with the application of 224 mg P kg^?1 of soil. Maximum shoot growth of corn was obtained with the addition of 323 mg P kg^?1 of soil. Most of the growth and yield components had significant positive association with grain yield or shoot dry weight. Phosphorus concentration and uptake were greater in the grain compared to straw in upland rice and dry bean plants. Overall, P-use efficiencies decreased with increasing P rates.     

Growth of Tropical Legume Cover Crops as Influenced by Nitrogen Fertilization and Rhizobia

Tropical legume cover crops are important components in cropping systems because of their role in improving soil quality. Information is limited on the influence of nitrogen (N) fertilization on growth of tropical legume cover crops grown on Oxisols. A greenhouse experiment was conducted to evaluate the influence of N fertilization with or without rhizobial inoculation on growth and shoot efficiency index of 10 important tropical cover crops. Nitrogen treatment were (i) 0 mg N kg^?1 (control or N₀), (ii) 0 mg N kg^?1 + inoculation with Bradyrhizobial strains (N₁), (iii) 100 mg N kg^?1 + inoculation with Bradyrhizobial strains (N₂), and (iv) 200 mg N kg^?1 of soil (N₃). The N?×?cover crops interactions were significant for shoot dry weight, root dry weight, maximal root length, and specific root length, indicating that cover crop performance varied with varying N rates and inoculation treatments. Shoot dry weight is considered an important growth trait in cover crops and, overall, maximal shoot dry weight was produced at 100 mg N kg^?1 + inoculation treatment. Based on shoot dry-weight efficiency index, cover crops were classified as efficient, moderately efficient, and inefficient in N-use efficiency. Overall, the efficient cover crops were lablab, gray velvet bean, jack bean, and black velvet bean and inefficient cover crops were pueraria, calopo, crotalaria, smooth crotalaria, and showy crotalaria. Pigeonpea was classified as moderately efficient in producing shoot dry weight.     

Phosphorus use efficiency of improved faba bean (Vicia faba) varieties in low‐input agro‐ecosystems

The use of phosphorus (P)‐efficient legumes is a prerequisite for sustainable intensification of low‐input agro‐ecosystems. A study was undertaken in a farmer's field in the tropical highlands of Ethiopia to assess the agronomic performance, P acquisition efficiency (PAE), and P utilization efficiency (PUE) of six improved faba bean varieties (Vicia faba L. var. CS‐20DK, Degaga, Gebelcho, Moti, Obse, Walki) without and with P application. Varieties showed significant variations in PUE, but P application had no significant effect on PUE. Variety Moti demonstrated highest PUE of 272 kg grain kg^?1 P, which was 1.6‐fold higher than the lowest PUE (164 kg grain kg^?1 P) of Gebelcho. PUE was significantly and positively correlated with grain yield (r = 0.542) and negatively correlated with shoot PAE (r = –0.541), indicating that PUE is important for grain yield. The results demonstrate that variations in grain and biomass yield of faba beans were largely due to differences in PUE and not due to PAE. Therefore, we argue that genetic resources of faba bean varieties showing optimal agronomic performance and high PUE in low‐input agro‐ecosystems should be better explored. Introduction of such varieties in low‐input cereal‐based cropping systems could improve and enhance P use efficiency at the system level.     

Effect of starter fertilizer in seed-row on emergence,biomass and nutrient uptake by six pulse crops grown under controlled environment conditions

Abstract

Legumes have a unique ability to obtain a significant portion of atmospheric nitrogen (N₂) through a symbiotic relationship with Rhizobia spp of bacteria but it takes time, thus, an early supply of N to the plant may positively influence growth and development. However, too much fertilizer in close proximity to the seed can damage the seedling. Therefore, this study was conducted to determine the maximum safe rates for starter seed-row fertilizer application under low seedbed utilization conditions (15%). Emergence, biomass yield and nitrogen (N), phosphorus (P) and sulfur (S) uptake responses to starter fertilizer products and blends applied at 0, 10, 20 and 30?kg?N?ha^?1 in the seed-row were investigated for six different pulse crops: soybean, pea, faba bean, black bean, lentil and chickpea. The general sensitivity (injury potential) for starter N, P, S fertilizer was lentil?≥?pea?≥?chickpea?>?soybean?≥?black bean?>?faba bean. Lentil, pea and chickpea could generally only tolerate the 10?kg?N?ha^?1 rates while soybean and black bean could tolerate 10–20?kg?N?ha^?1. Faba bean emergence appeared relatively unaffected by all three rates of N and showed least sensitivity to seed row placed fertilizer. In terms of 30-day biomass response, soybean and black bean were most responsive to fertilization, while pea, faba bean, lentil and chickpea were least responsive to the starter fertilizer applications, with no benefit increasing above the 10?kg?N?ha^?1 rate.     

Citric acid loaded nano clay polymer composite for solubilization of Indian rock phosphates: a step towards sustainable and phosphorus secure future

Non-renewable nature of rock phosphate (RP) reserves coupled with open ended nature of P cycle makes it imperative for maximum utilization of available P resources. In this context, use of Indian RPs from Purulia and Udaipur along with citric acid loaded nanoclay polymer composite (CA-NCPC) as P source to costly diammonium phosphate (DAP) was investigated through an incubation experiment followed by a greenhouse experiment with wheat-rice cropping sequence in a Luvisol (pH 5.14, available P 13.5 mg kg^?1). Soil available P, crop yield parameters and dynamics of soil P fractions were taken to judge the efficacy of CA-NCPC in solubilizing RPs. Application of CA-NCPC and DAP resulted in 82% and 69% increase in available P over control, respectively under incubation study. Direct effect of treatment receiving CA-NCPC + RP on yield and P uptake by wheat was comparable with DAP but residual impact of CA-NCPC + RP (16.7 g pot^?1) was better than DAP (13.8 g pot^?1) in rice. The changes in inorganic P fractions were also significant as inclusion of RP increased calcium-P from 16.1 to 61.5 mg kg^?1. Results indicated potentiality of RPs treated with CA-NCPC as an alternate P source which could prove promising amidst P scarcity.     

Response of interspecific and sativa upland rices to Mali phosphate rock and soluble phosphate fertilizer

In West Africa, two-thirds of upland rice is grown on acidic phosphorus (P)-deficient soils. Phosphorus is one of the most limiting-nutrients affecting crop productivity. A three-year field experiment was conducted on a Ferralsol in Côte d'Ivoire to study the response of four interspecific rice cultivars and a sativa (control cultivar) to Tilemsi phosphate rock (PR) and soluble triple superphosphate (TSP) fertilizer. PR was applied at 0, 150, 300, and 450 kg ha^?1 P once in the first year and residual effects were measured in the following years. TSP (0, 50, 100 and 150 kg ha^?1 P) was applied yearly. More significant yield increasing (38%) was observed in the second year. Annual application of 50 kg P ha^?1 as TSP or a one-time application of 150 kg P ha^?1 as PR was the optimum rate for the production of all cultivars. Higher rates of P from TSP (100 and 150 kg P ha^?1) gave 2–3 times greater residual P in soil than the optimum rate, inducing no further response of rice. Two interspecific cultivars were identified as the most acid- and low P-tolerant cultivars for improving rice production in West Africa humid forest zone.     

RESPONSE OF SOYBEAN TO SOIL APPLIED SULFUR AND BORON IN A CALCAREOUS SOIL

A greenhouse experiment with soybean grown on sulfur (S) and boron (B) deficient calcareous soil was conducted for two years in northwest India to study the influence of increasing sulfur and boron levels on yield and its attributing characters at different growth stages (55 days, maturity). The treatments included four levels each of soil applied sulfur viz. 0, 6.5, 13.4, 20.1 mg S kg^?1 and boron viz. 0, 0.22, 0.44, 0.88 mg B kg^?1 at the time of sowing. The highest dry matter yield at 55 days after sowing, DAS (19.3 g pot^?1) and maturity (straw yield ?25.2 g pot^?1 and grain yield ?7.3 g pot^?1) was recorded with B_0.44 S_13.4 treatment combination. The combined applications of sulfur and boron yielded highest oil content with B_0.44S_13.4 (21.7%) treatment level. Chlorophyll ‘a’ and ‘b’ increased significantly with successive levels of sulfur and boron addition at 55 DAS. The mean sulfur and boron uptake in straw and grains increased significantly with increasing levels of sulfur and boron up to 13.4 mg kg^?1 and 0.44 mg kg^?1 and decreased non-significantly thereafter. At both the growth stages, a synergistic interactive effect of combined application of sulfur and boron was observed with B_0.44 S_13.4 treatment level for sulfur and boron uptake in straw and grains.     

Growth,yield and yield components of dry bean as influenced by phosphorus in a tropical acid soil

Phosphorus (P) deficiency is one of the most yield limiting factors for dry bean (Phaseolus vulgaris) production in tropical acid soils. Dry beans are invariably grown as mono-crops or as inter-crops under the perennial tropical crops. Information is limited regarding the influence of phosphorus fertilization on dry bean yield and yield components and P use efficiency in tropical acid soils. A greenhouse experiment was conducted to evaluate the influence of phosphorus fertilization on dry bean growth, yield and yield components and P uptake parameters. Phosphorus rates used were 0, 50, 100, 150, 200, and 250 mg P kg^?1 of soil. Soil used in the experiment was an acidic Inceptisol. Grain yield, shoot dry weight, number of pods, and 100 grain weight were significantly (P < 0.01) increased with phosphorus fertilization. Maximum grain yield, shoot dry matter, number of pods, and 100 grain weight were obtained with the application of 165, 216, 162, and 160 mg P kg^?1 of soil, respectively, as calculated by regression equations. Grain yield was significantly and positively associated with shoot dry weight, number of pods, P concentration in grain and total uptake of P in shoot and grain. Phosphorus use efficiency defined in several ways, decreased with increasing P rates from 50 to 250 mg P kg^?1 of soil. Maximum grain yield was obtained at 82 mg kg^?1 of Mehlich 1 extractable soil P. Results suggest that dry bean yield in Brazilian Inceptisols could be significantly increased with the use of adequate rates of phosphorus fertilization.     

浙江红壤性水稻土油菜-水稻-水稻轮作制中磷矿粉的管理

为了探明磷矿粉在油菜-水稻-水稻轮作制中的有效施用方法，在一个发育于第四纪红色黏土的酸性水稻土上进行了3a田间试验。试验结果显示：施用磷肥对油菜的增产效应显著比水稻大。当将过磷酸钙P120kg hm^-2分施于油菜、早稻和晚稻，而将磷矿粉P120kg hm^-2集中施于油菜时，油菜的增产效应：Gafsa磷矿粉〉昆阳磷矿粉〉过磷酸钙；早稻的增产效应：Gafsa磷矿粉≈昆阳磷矿粉〉过磷酸钙；晚稻的增产效应：过磷酸钙〉Gafsa磷矿粉〉昆阳磷矿粉。Gafsa磷矿粉和昆阳磷矿粉对油菜、早稻和晚稻的相对农学有效性分别为108．7％、105．0％、99．6％和89．4％、104．8％、97．1％。增加磷矿粉用量或将磷矿粉与过磷酸钙混合分施于3季，并未增加油菜和水稻的产量。油菜收获后的耕层土壤有效磷含量高于水稻收获后的耕层土壤有效磷含量。耕层土壤有效磷含量与油菜相对产量之间呈显著的正相关，而与水稻相对产量之间则无显著的相关性。     

Enhancing nutrient translocation,yields and water productivity of wheat under rice–wheat cropping system through zinc nutrition and residual effect of green manuring

Abstract

Efficient nutrient and water use are two important considerations to obtain good harvests of wheat. This necessitates the development of an effective nutrient management technique that not only increases yield, but simultaneously can save nutrient and water use. In this context, a field experiment was conducted at Indian Agricultural Research Institute, New Delhi, India to evaluate the residual effect of sesbania and rice bean (in-situ), subabul (ex-situ) green manuring and Zinc (Zn) fertilization, using chelated Zn-ethylenediaminetetraacetic acid (Zn-EDTA) on nutrient use, yields and water productivity of wheat under rice–wheat cropping system. Among residual effects of green manure crops and Zn fertilization, sesbania and foliar spray of 0.5% chelated Zn-EDTA at 20, 40, 60 and 80 days after sowing (DAS) recorded significantly higher nutrient content and uptake and yields than other green manure crops and Zn treatments. Residual effect of sesbania saved about 46.5?×?10³ and 30.5?×?10³ L irrigation water per tonne of wheat over subabul and rice bean, respectively. Foliar spray of 0.5% chelated Zn-EDTA at 20, 40, 60 and 80 DAS saved about 55.5?×?10³, 47?×?10³ and 13?×?10³ L irrigation water per tonne wheat over residual effect of 5?kg Zn ha^?1 through chelated Zn-EDTA as soil application, 2.5?kg Zn ha^?1 through chelated Zn-EDTA as soil application + 1 foliar spray of 0.5% chelated Zn-EDTA at flowering and foliar spray of 0.5% chelated Zn-EDTA at active tillering?+?flowering?+?grain filling, respectively. Correlation analysis showed positive correlation between Zn uptake and grain yield.     

Soil Phosphorus Management Based on the Agronomic Critical Value of Olsen P

Fertilizer phosphorus (P) is generally added to agricultural soils to meet the needs of crop production. In this study, the crop yield and soil Olsen P were measured every year (5–18 years) at 16 winter wheat (Triticum aestivum L.) –maize (Zea mays L.) crop rotation sites in cinnamon soil (Luvisols in FAO system). The mean agronomic critical value of Olsen P for maize was 14.2 mg kg^?1 and for winter wheat was 14.4 mg kg^?1 when using the Liner-plateau and Mitscherlich models. The change in soil Olsen P was positively linearly correlated with the P budget (P < 0.01), and an increase of 4.70 mg kg^?1 in soil Olsen P for each 100 kg ha^?1 of P budget in the 0–20 cm soil layer. A model of P fertilizer recommendation rate that integrated values of the change in soil Olsen P in response to P budget and the agronomic critical value of Olsen P was used, in order to adjust current levels of soil Olsen P to the agronomic critical value at the experimental sites over the next 5 years, P fertilizer application rate should be in the range of 0–87.5 kg P ha^?1.     

Zinc nutrition of rice as influenced by crop establishment methods,rates of nitrogen and phosphorus fertilization and inoculation with microbial consortia

Abstract

Zinc (Zn) fertilization in rice is important to enhance productivity and increase Zn concentration in rice grain to improve its nutritional status. A field experiment was conducted in wet seasons of 2013 and 2014 to study Zn nutrition of rice in three different crop establishment methods (CEMs) viz. puddled transplanted rice (PTR), system of rice intensification (SRI) and aerobic rice system (ARS), under three different rates of nitrogen (N) and phosphorus (P) viz. 0, 75 and 100% of recommended dose of fertilizer (RDF) (120?kg N ha^?1 and 25.8?kg P ha^?1) and two different sources of N and P viz. chemical fertilizer and microbial inoculation (MI). Concentration and uptake of Zn at different growth stages and in straw and milled rice was significantly higher in PTR and SRI than ARS. Soil DTPA–extractable Zn content of soil was increased by 1142.4, 1140.3 and 755.8?g ha^?1 in PTR, SRI and ARS after two year of Zn fertilization (soil application of 5?kg Zn ha^?1). Zinc nutrition increase its Zn concentration in straw and milled rice and improvement in total uptake was 38.1, 40.3 and 40.8?g ha^?1 when Zn was applied with RDF, 75% RDF + Anabaena sp. (CR1) + Providencia sp (PR3) consortia (MI1) and 75% RDF + Anabaena-Pseudomonas biofilmed bio-fertilizer (MI2), respectively. Positive correlation between milled rice yield and Zn concentration (R²= 0.95 and 0.97) showed the importance of Zn nutrition in improving rice yield. Zinc concentration at 70?days after sowing (DAS) and 100 DAS was also found positively correlated with dehydrogenase activity and microbial biomass carbon in soil.     

Phosphorus accumulation, leaching and residual effects on crop yields from long-term applications in the subtropics

The effects of 25 years of annual applications of P fertilizer on the accumulation and migration of soil Olsen‐P, and the effects of soil residual P on crop yields by withholding P application for the following 5 years, were evaluated in a subtropical region. Annual application of P fertilizer for 25 years to crops in summer (groundnut), winter (wheat, mustard or rapeseed) or in both seasons raised the Olsen‐P status of the plough layer (0–15 cm) from initially very low (12 kg P ha^?1) to medium (18 kg P ha^?1) and very high levels (40–59 kg P ha^?1), depending on the amount of P surplus (amount of fertilizer applied in excess of removal by crops) (r = 0.86, P ≥ 0.01). However, only 4–9% of the applied P fertilizer accumulated as Olsen‐P to a depth of 15 cm (an increase of 2 mg kg^?1per 100 kg ha^?1 surplus P) in the sandy loam soil. In the following 5 years, the raising of 10 crops without P fertilizer applications decreased the accumulated Olsen‐P by only 20–30% depending upon the amount of accumulated P and crop requirements. After 29 years, 45–256 kg of residual P fertilizer had accumulated as Olsen‐P ha^?1 in the uppermost 150 cm with 43–58% below 60 cm depth; this indicates enormous movement of applied P to deeper layers in this coarse textured soil with low P retention capacity for nutrients. Groundnut was more efficient in utilizing residual P than rapeseed; however, for both crops the yield advantage of residual P could be compensated for by fresh P applications. These results demonstrated little agronomic advantage above approximately 20 mg kg^?1 Olsen‐P build‐up and suggested that further elevation of soil P status would only increase the risk of environmental problems associated with the loss of P from agricultural soils in this region.     

Variation in the nutritional quality of rice straw and grain in response to different nitrogen levels

Abstract

Nitrogen (N) applied through urea is essential for rice crops and usually it is the most yield-limiting nutrient in irrigated rice production around the world. A field experiment was conducted to evaluate the effect of nitrogen levels (0, 90,120, and 150?kg?ha^?1) on the nutritional quality of straw and grain of rice varieties, PR 111, PR 122, and Pusa 44. In rice straw, significant interaction between nitrogen levels and all proximate components was observed. Increase in nitrogen level increased the crude protein by 69.23% (dry matter basis) whereas the neutral detergent fiber, acid detergent fiber, and cellulose content decreased by 7.82%, 11.18%, and 14.16%, respectively. In rice grain, crude protein content, starch content, and gel consistency were positively related to increase in nitrogen levels. Therefore, increase in nitrogen fertilization led to improved nutritive quality of both straw and grain for use as feed resource and human consumption, respectively.     

Bioavailability of Silicon from Different Sources and Its Effect on the Yield of Rice in Acidic,Neutral, and Alkaline soils of Karnataka,South India

Several silicon (Si) sources have been reported to be effective in terms of their effectiveness on rice growth and yield. Apart from that, it is crucial to understand the bioavailability of silicon from different silicon sources for adequate plant uptake and its performances in varying types of soils. In this point of view, a pot experiment was conducted to assess the bioavailability of silicon from three Si sources and its effect on yield of rice crop in three contrasting soils. Acidic (pH 5.86), neutral (pH 7.10), and alkaline (pH 9.38) soils collected from different locations in Karnataka were amended with calcium silicate, diatomite, and rice husk biochar (RHB) as Si sources. Silica was applied at 0, 250, and 500 kg Si ha^?1, and the pots were maintained under submerged condition. There was a significant increase in the yield parameters such as panicle number pot^?1, panicle length pot^?1, straw dry weight pot^?1, and grain weight pot^?1 in acidic and neutral soils with the application of Si over no Si treatment, whereas only straw dry weight pot^?1 increased significantly with the application of Si sources over control in alkaline soil. Higher Si content and uptake was noticed in neutral soil followed by acidic and alkaline soils. The bioavailability of Si increased with the application of Si sources but varied based on the types of soil. Application of calcium silicate followed by diatomite performed better in acidic and neutral soils whereas RHB was a better source of Si in alkaline soil. A significant difference in plant-available silicon status of the soil was noticed with the application of Si sources over control in all three studied soils.     

BORON AND LIME EFFECTS ON YIELD AND DEFICIENCY SYMPTOMS OF RICE GROWN IN GREENHOUSE ON ACID TYPIC GLOSSAQUALF*

ABSTRACT

No boron (B) deficiencies have been reported for rice (Oryza sativa L.) grown in the United States and, when occurring elsewhere, reports often lack details of deficiency symptoms and leaf-B critical values. An experiment was conducted to determine the effect of B and lime on yield, pollen viability, and to determine diagnostic symptoms of B deficiency in rice. Rice cv. “Bengal” was grown in the greenhouse on a soil acquired from a rice farm from SW Louisiana in the United States, a Caddo silt loam (Caddo sl) (Typic Glossaqualf, fine-silty, siliceous, thermic), treated with 0.44?mg?B?kg^?1 (+B) or no B (?B). Split plots were limed at rates of (i) none; (ii) 224?mg?kg^?1 CaO+40.3?mg?kg^?1 MgO; and (iii) 673?mg?kg^?1 CaO+121?mg?kg^?1 MgO. Rice was also grown in ?B and +B potting media and in ?B sand culture using nutrient solution identical to that used in other studies of ours. Rough-rice yields from the +B Caddo sl treatment was 11% higher than from the ?B treatment (29.3 vs. 26.3?g?pot^?1; P=0.02). The yield increase was likely due to fewer damaged pollen (8%) found from the +B than the ?B treatment (17%; P=0.014). Leaf-B at tillering was 11.3?mg?kg^?1 for the B-treated rice and 7.1?mg?kg^?1 from the ?B treatment. Liming did not significantly affect leaf B or yields. Boron deficiency symptoms were found only in the ?B sand-culture where yields were 1.1?g?pot^?1, 96% less than that from the +B Caddo sl. Symptoms were like those found in our earlier hydroponic studies with twisted and whitish leaf tips starting at tillering and 1-cm white bands across the width of leaves. Maturity was delayed about four weeks. Boron deficiency from the Caddo sl and sand treatments occurred with leaf B≤7?mg?kg^?1 and with a Caddo sl soil B of 0.18?mg?hws (hot-water soluble) B?kg^?1. Given that no B deficiency symptoms were found in rice experiencing moderate yield loss grown on the rice soil, one must rely on soil and plant analyses to help detect likely candidates for moderate B deficiency.     

Crop production impacts on soil phosphorus removal and soil test levels

An 8-year field study documented the impact of tillage, crop rotations, and crop residue management on agronomic and soil parameters at Brookings, South Dakota. The greatest annual proportion of above-ground biomass phosphorus (P) removed was from the grain (78–87% of total) although crop residue removed some P as well. Greater above-ground total biomass P (grain P + crop residue P) was removed from corn than from soybean and spring wheat crops mainly due to the greater corn grain biomass harvested. Cumulative above-ground biomass P removal was greatest for the corn-soybean rotation (214 kg P ha^?1), while it was lowest for the soybean-wheat rotation (157 kg P ha^?1). Tillage treatments within crop rotation or residue management treatments did not influence annual or cumulative P removal rates. Olsen extractable soil orthophosphate-P levels declined consistently through time from a mean of 40 µg g^?1 (2004) to 26 µg g^?1 (2011). Biomass P removal was calculated to be 15.7 ha^?1 yr^?1 to decrease Olsen extractable soil orthophosphate-P levels by 1 µg g^?1 yr^?1 over 8 years of the study.