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Young, fully expanded leaves of 'Hass' avocado on clonal 'Duke 7' rootstock, 2 years from budding, were used to assess changes in leaf NH3-NH4 content. Foliar application of 1.5 g low biuret urea per tree failed to increase the leaf NH3-NH4 content: compare 23.6 ± 5.8 versus 20.1 ± 5.7 μg NH3-NH4 per g fr. wt. leaf tissue (x ± STD. DEV., N = 3 trees per treatment) from trees treated with and without urea, respectively (Nevin and Lovatt, 1989). Foliar application of 1.5 g of low biuret urea per tree to 5-yearold rooted cuttings of the 'Washington' navel orange of comparable size increased the leaf NH3-NH4 content of the trees subjected to 4, 6, or 8 weeks of low temperature 1.7-, 2.2-, and 1.2-fold, respectively.

Leaf analysis has been widely used to formulate fertilizer applications for citrus trees. Results of leaf analysis vary with age and position of the leaves sampled. The prevalent methods are to sample 4 to 7 months old spring flush leaves from the nonfruiting terminals and leaves from behind the fruit (fruiting terminal). We have reported significant differences between the leaves taken from two positions for 10 of the 12 elements analysed. Our long-term studies were aimed at developing a model conversion factor for leaf analysis based on samples taken from fruiting and nonfruiting terminals. A regression analysis was performed on a four years data set for 5 elements showing significant differences between two categories of leaves. Highly significant (P

Starting in 1970, an “on” year for fruit set, young Valencia orange fruit were thinned in July, September, and November. Degrees of thinning were 0, 33, 66, and 100 per cent. Leaf samples were taken in 1971 for carbohydrate analysis. The fruiting cycle was almost completely reversed when all of the young fruit were removed in July. Less fruit removal or removal at a later date was progressively less effective. Thinning had no effect on the size of the fruit remaining on the tree. In the year after thinning, fruit size was inversely related to number of fruit on the tree. The amount of fall growth in 1970 was increased by fruit removal. Likewise, the spring growth in 1971 was earlier and more extensive on the trees that were 100 per cent thinned in July, 1970. Carbohydrates in the leaves were mainly starch, sucrose and one unidentified compound. Also present were small amounts of fructose, glucose, malic acid, myo-inositol, and one other unidentified soluble carbohydrate. There was a positive correlation between the fruit set in the spring of 1971 and the concentration of starch in the leaves before the beginning of 1971 spring growth. During the June drop period, there was an increase in leaf starch, but not in sugar, associated with an increase in degree of thinning. At the end of the June drop period, there were no significant differences in starch or sugar content. Data presented in this study indicate that carbohydrates, in the amounts present, were not limiting for fruit set.

Fifty-six “experiment-years” of citrus data are presented which show that kilogram for kilogram, foliar-applied N was as effective as soil-applied N for fruit production. However, while one annual soil application sufficed to supply adequate N, three to six or more foliar sprays per year were required. “N-production efficiency” (kg fruit produced per kg applied N) varied from 97 to 484. At or near the maximum nutritionally-attainable yield, “fruit-N-removal efficiency” (kg N removed in fruit per kg applied N × 100) varied from 11 to 75%. The kg of N per 1,000 kg of fresh California citrus fruit varied from 1.15 to 1.73 and increased with increasing N rates.

Reference values were derived from field data for use in evaluating the N, P, K, Ca, and Mg status of ‘Valencia’ orange (Citrus sinensis [L.] Osbeck) trees by the Diagnosis and Recommendation Integrated System (DRIS). DRIS diagnoses generally agreed with diagnoses made by the sufficiency range method, with the advantage that DRIS reflects nutrient balance, and identifies the order in which nutrients are likely to become limiting. DRIS diagnoses were affected by the type and age of the tissue sampled. DRIS reflected changes in nutrient concentrations due to alternate bearing or crop load effects and agreed with the sufficiency range method when concentration changes were sufficient to affect the latter method.

Several factors associated with creasing of oranges were observed and measured in a number of California field studies for more than a decade. Severity of creasing was found to be highly correlated with incidence. Creasing was highly variable among trees in a given orchard; occurred more frequently on the south half of the tree than on the north half; developed first on the side of the fruit facing the trunk; and became progressively more severe as the fruit aged. It was also associated with greater crop loads. Peel and juice composition were significantly different between creased and noncreased fruit from the same tree. Split or summer applications of nitrogen resulted in less creasing than spring applications; the effects of nitrogen rate were not consistent. Trees deficient in phosphorus in respect to volume yield produced fruit that had less creasing than phosphorus-sufficient trees, but the nutrient had no effect when applied beyond correction of the deficiency. Soil applications of potassium reduced creasing; potassium nitrate sprayed on foliage even after creasing was evident reduced creasing at harvest time. Over a ten-year period in one experiment, creasing was associated positively with the range between the mean minimum temperature for June and the mean maximum for July, also with the range between the mean minimum for December 15 to January 15 and the mean maximum for January 15 to February 15. Certain trees were consistently high in fruit yield and low in incidence of creasing. This suggests that a genetic factor might be influential.

The beginning of coal mining, like most other things, is enveloped in the obscurity of the past. There is little doubt that coal, so far as can be gathered from scattered notices discovered here and there in various records, was first obtained by manual labour from the outcrops on hill sides or the margins of brooks and rivers, or the cliffs of the sea coast. In such places the attention of the ancient people would be arrested by the contrast of the black mineral with the colour of the superincumbent and the adjacent strata. The use of coal and other mineral substances did not become general until the necessity for their use became apparent, nor were they at first extensively worked. In ancient British and Roman times coal could not have escaped the notice of the energetic people of the land, though the forests that then covered the greater part of England afforded abundant supplies of fuel. The Romans, as we shall see, had discovered coal and its uses, or had derived their knowledge from the Britons. In Anglo-Saxon and in Norman times, as manufactories of various kinds were established and increased in number and extent, the forests suffered in proportion. The iron and glass works which were carried on extensively in the northern and eastern parts of England consumed increasingly enormous quantities year by year; the forests diminished, and the use of wood as fuel became more and more costly. This destructive process had the effect of directing public ...

‘Prior Lisbon’ lemon trees were treated with increasing rates of N fertilizer up to 6 lb. N per tree per year. Likewise, ‘Monroe Lisbon’ lemon trees were treated with up to 4 lb. N per tree per year. Also, for the Trior Lisbon/one treatment was 6 urea foliage sprays per year which supplied about 2 lb. N per tree per year. For the Trior Lisbon’ there was a tendency for yields to increase with increasing N rates with the high rate yielding significantly more than the low rate. Yield was highly correlated with leaf N with maximum yield occurring at about 2.2% leaf N. Urea foliage sprays maintained leaf N and maximum yield. Fruit quality was not adversely affected by increasing N. As with Prior ‘Lisbon’, ‘Monroe Lisbon’ yields increased with increasing N but the maximum yield occurred at about 2.5% leaf N. Yields from single N applications were not different from split N applications.

In a 5-year factorial fertilizer experiment, an increase in leaf N from 2.54 to 2.71% by soil applications of urea, reduced creasing and fruit size and increased green color on the fruit at harvest. Leaf K was increased from 0.47 to 0.67% by soil application of K2SO4 and to 0.65% by foliar application of KNO3; except for degree of fruit color and leaf N content, effects of soil- and foliar-applied K differed little and both increased yield, fruit size, and green color on the fruit and reduced creasing. Increasing leaf P from 0.132 to 0.139% had little influence on factors influencing the value of the fresh-fruit crop. Gibberellic acid (GA) sprays increased green color on the fruit and reduced creasing. The effects of N, K, and GA on reducing creasing and increasing green color on the fruit were strongly additive. There was an inverse relation between creasing and green color of fruit. Each problem can be reduced but at the expense of the other, and both problems cannot be reduced simultaneously. Packinghouse statements showed that monetary returns/tree were increased about 75% by K treatments without GA; 17% with GA alone; 61% with GA + soil-applied K; and 42% with GA + foliar-applied K.

The establishment of a Museum in connection with the Society was suggested by the Earl Fitzwilliam, at an early period of the Society’s existence, and its extension has at all times occupied the serious attention of the Council. The object of its establishment was to obtain a “complete and classified collection of the Fossils of the Coal Field, arranged according to the strata in which they were found, and of other Minerals, which would serve to throw light on the Geology of the district.” In part, this object has been carried out. Apartments have been engaged by the Council at Wakefield, in which to place and arrange such specimens as may be presented to the Society, but they are ill adapted to the purpose; however, it is to be hoped that the members, the public generally, and the gentlemen of the county in particular, whose interest is so intimately and inseparably connected with the object which this Society proposes to investigate, will not long allow our “medals of creation” to remain hidden in the dusky recesses of a forsaken wool warehouse. But still, if a splendid Museum be erected for our present collection, much remains to be done, and much may be done, if we all work together, and really and truly do our best to render the Museum, (what I trust and hope it will be one day,) the boast of the West Riding. Some gentlemen say “I don’t know of any thing worth sending to the Museum;” another ...

SynopsisLeaching and volatile losses of N from some southern California soils were studied when various nitrogenous fertilizers were broadcast and unincorporated. Under sprinkler irrigation, substantial leaching losses occurred with Ca(NO₃)₂. Manure was an inefficient source of N. Substantial volatile losses of NH₃ occurred with urea on calcareous as well as acid soils. In comparative studies of atmospheric NH₃ loss, the order of magnitude was urea>(NH₄)₂SO₄>NH₄NO₃> urea-formaldehyde.

The history of nitrogen usage on oranges in California shows that prior to about 1960 many growers were using more nitrogen than was needed to produce the crop. In some areas nitrogen usage is now less than half of what it was prior to 1960. The reduction was associated with increased commercial usage of leaf analysis as a guide to nitrogen fertilization. Also since 1960, as a result of the decrease in fertilizer applied, the annual per‐acre amounts of fertilizer nitrogen that were subject to leaching in the Santa Ana Watershed were reduced by an estimated 50 percent in Riverside County and about 80 percent in San Bernardino County.

Where Mg deficient ‘Washington’ navel orange trees were sprayed with Mg, leaf Mg was increased from a deficient to an optimum level in the first year of application. However, it was not until the fourth year of application that a yield increase occurred. At least 2 sprays annually were required. There was an increase in total soluble solids in the juice as a result of the sprays, but there were no other consistent effects on fruit quality. Magnesium in the feeder roots was increased by the foliage sprays. Leaf K was decreased by the Mg sprays. One year after cessation of the sprays the leaf Mg was again in the deficiency range.

Mr. Embleton next read his paper, illustrated by sections “On the Order of Succession of the Coal Seams in the Northern Coal Field of Yorkshire.” The subject of discussion on this paper was confined to a consideration of the order of the various seams found in the Township of Whitwood, Methley, Stanley, Wrenthorpe, Lofthouse, Rothwell, Ardsley, Middleton, and Beeston. Mr. Embleton commenced his paper by saying it would be of great importance to the society if the order of the seams of coal were determined in each district, and that it was the only sure foundation for comparison with distant parts of the coal field. He remarked that it was only by a careful collection of shaft sections that many important questions in local geology could be satisfactorily cleared up. As for instance, the thinning or thickening of certain seams in particular directions, the existence of seams at one colliery which were not found in an adjoining one, the origin of coal itself. They would also show when that variety of coal, called cannel coal, was chiefly found, and whether, as had been often stated, though, perhaps, without much foundation, it was only found in the vicinity of certain throws. The workable seams in the Townships before mentioned are the Stanley Shale Coal, the Stanley Main Coal, the Warrenhouse Coal, the Lofthouse or Haigh Moor Coal, the Fish Coal, the 40 Yards Coal, the Yard Coal or Little Coal, and the Main or Deep Coal of the Rothwell Haigh and ...

Yield of young lemon trees increased with either soil application of K2SO4 or foliage application of KNO3 in an orchard where leaf K was low. Leaf Zn was low but one annual foliage spray of ZnSO4 (control in this study) supplied adequate Zn and there was no response to additional Zn sprays. Peel thickness decreased, and percent juice and percent acid in the juice increased with added K.

Sprays of ammonium ethyl carbamoyl-phosphonoate (Krenite), applied to the tops of mature Lisbon lemon trees [Citrus limon (L). Burml.] resulted in significant inhibition of re-growth for over 3 years. One spray increased yield over the control trees (hand topped annually), while 2 sprays reduced yield. The sprays did not effect the N concentration in the leaves.

By far the most important subtropical fruit is citrus and the most widely grown citrus is the sweet orange. Lemon and grapefruit also are important citrus species. Other important subtropical fruits are dates, figs, and olives. Tropical fruits are most numerous in kinds, and a few, such as the avocado, litchi and mango are grown on a commercial scale in the subtropical regions. Others, such as bananas, pineapples, coffee, and papaya, are strictly tropical. It is not an uncommon practice to apply K, but it is done in many cases without a demonstrated need. With the realization of the broad effects of K, such a practice should not be followed, but K level should be adjusted to give optimum response for both quality and yield. For this diagnostic methods and standards are required.

An increase in the K level in orange and grapefruit trees generally increases the thickness of the peel and reduces the percentage of juice in the fruit. Data presented in this report show that an increase in K in the lemon tree has the opposite effect as that which occurs in the orange and grapefruit tree. An increase in the level in lemon trees resulted in thinner peels and in a higher percentage of juice in the fruit.

Carbohydrate (CHO) accumulation in ‘Valencia’ orange leaves, sampled in February, was inversely related to the fruit load on the tree at the time of sampling but directly related to the amount of fruit produced from the flowering which followed the time of leaf sample. Late harvest reduced fruit production in the following year but did not significantly alter CHO accumulation.

Starch in the roots of mandarin trees (Citrus reticulata Blanco cv. Kinnow) was drastically reduced by an “on” crop. This was related to prolonged bud dormancy, delayed spring growth and an “off’ crop the following year.

Field experiments in the past on Valencia orange trees in California have not shown any clear K deficiency as indicated by the effects of K applications on numbers of fruit produced per tree. Such experiments were established with little knowledge of the initial K nutritional status of the trees in question. Commercial use of citrus leaf analysis as a diagnostic tool has increased in recent years, and through this medium an orchard was found near Escondido, California with leaf K levels which indicated possible K deficiency. Some of the initial results of an experiment in this orchard are given in Table 1.