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Visual Symptoms of Nutrient Deficiency in Axonopus compressus (Cow Grass)



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Research Technical Note
Urban Greenery Series RTN
Visual Symptoms of Nutrient Deciency in
Axonopus compressus (Cow Grass)
Author: Chin Siew Wai
Turfgrass nutrition plays an important role in maintaining the vigour and density of a lawn. Nutri-
ents are essential to support proper plant growth and development. When available in adequate
amounts, they enable plants to better adapt to environmental stress, tolerate human trac im-
pacts as well as combat invasion by weeds. Macronutrients such as nitrogen (N), phosphorous (P)
and potassium (K) are required in large amounts by plants for the formation of new roots, shoots,
expansion of leaf tissues and chlorophyll pigment synthesis while micronutrients like iron (Fe) is
closely involved in the synthesis of chlorophyll pigments.
Plants obtain nutrients from the soil substrate. Nutrients may be lost when soil leaches or when
plant tissues are removed during mowing operation. In addition, nutrients in the soil may also
be converted to forms that are unavailable for plant uptake under suboptimal soil conditions.
Therefore, it is important to apply fertilizers to replace the nutrients lost after several regular
mowing regimes or ameliorate the soil conditions to make nutrients available.
Visible symptoms of nutrient deciency are usually expressed only when nutrient levels within
the plant tissues fall below minimum critical levels that aects growth. It is useful to be able to
recognize early symptoms of nutrient deciency and apply corrective measures. This helps to
prevent the lawn quality from degrading.
This Research Technical Note (RTN) documents the early visual symptoms of nutrient deciencies
(N, P, K and Fe) in Cow Grass (Axonopus compressus) under controlled nutrient deciency condi-
tions. Coupled with experience and knowledge of the site conditions, this RTN can serve as a
diagnostic guide for operational managers.
Fig. 1 Cow Grass (A xonopus com-
pressus) lawn with complete nutri-
tion is green and dense
Visual Symptoms of Nutrient Deciency in Axonopus compressus (Cow Grass) RTN 14-2013
Nutrient deciency symptoms in Cow Grass
Nitrogen deciency symptoms
The mature leaves rst became yellowish-green with
reddish-purple streaks spreading from bases of leaves
towards the tips [Figs. 2A & B ‘N2’]. The mature leaves
turned entirely reddish-purple [Figs. 2B ‘Red’ & 2C], be-
came necrotic and caused the leaf to wither and die
(Figs. 2B & C).
When deciency persisted, young leaves too became
yellowish-green (Fig. 2B ‘N1’). The shoot density re-
duced; the lawn thinned out and weeds started to es-
tablish (Figs. 2C, D & E)
Fig. 2A
Fig. 2D
Fig. 2B
Fig. 2C
Fig. 2E
Visual Symptoms of Nutrient Deciency in Axonopus compressus (Cow Grass) RTN 14-2013
Phosphorous deciency symptoms
Potassium deciency symptoms
Both mature and young leaves rst became uniformly
dark green (‘Phosphorous’ in Fig. 3A). The mature leaves
then turned dark purple with the pigment spreading
from the tip towards the base (Fig. 3B). The leaf tips of
the dark purple leaves became necrotic. Necrosis soon
spreads from leaf tip; causing the leaf to wither and die.
The phosphorous deciency symptoms diered from ni-
trogen deciency symptoms in which the mature leaves
rst became yellowish-green before the accumulation of
reddish-purple pigments that spread from leaf base to
leaf tip (‘Nitrogen’ in Fig. 3A & Figs. 2A, B & C)
The mature leaves rst became greenish-yellow. Ne-
crosis was observed as either small dark-brown spots
distributed randomly throughout the entire leaf (Fig.
4A) or as necrotic areas on the leaf margin (Fig. 4B) or at
the leaf tip (Fig. 4C). Necrosis soon spreads towards the
leaf base, causing the leaf to wither and die. Some of
the mature leaves wilted, mimicking a drought-stressed
Fig. 3A
Nitrogen Phosphorous
Fig. 3B
Fig. 4A Fig. 4B
Fig. 4C
Visual Symptoms of Nutrient Deciency in Axonopus compressus (Cow Grass) RTN 14-2013
Iron deciency symptoms
Applications and Limitations
• Nutrient deciency symptoms described in this RTN for Cow Grass could be used as a guide
to diagnose deciency conditions. For example, the distinct early symptoms of N and Fe de-
ciencies can be used with certainty as diagnostic tool to detect nitrogen and iron nutri-
ent deciency problem. However, it has its limitations when used to detect early deciency
symptoms of phosphorous and potassium, as symptoms are subtle and less discernible.
• One must consider the complex interactions between nutrient availability and soil pH, avail-
able soil moisture, soil oxygen levels, excesses of other nutrients, and organic matters when
interpreting the visual symptoms in order to accurately rectify the problem. Examples of such
interactions include (1) alkaline soil pH (pH > 7.0) resulting in iron to exist in insoluble Fe (III)
form that is unavailable to the plant and (2) waterlogged wet soil condition resulting in high
bicarbonate content, which restricts root uptake of iron. Therefore, accurate diagnosis of a
nutrient deciency condition cannot be based on visual symptoms alone and must be ac-
companied with soil or tissue nutrient testing.
• Routine fertilization regime with complete fertilizers, preferably 4:1:2 (N: P: K), is a positive
approach to prevent the onset of nutrient deciencies and ensure the vigorous and healthy
growth of Cow Grass plants. Conversely, if other interacting factors such as suboptimal soil
pH (too acidic or alkaline soil) or poor soil aeration (waterlogged condition) are not remedi-
ated, correction of nutrient deciencies by supplying the associated nutrients may not be
The young leaves rst displayed interveinal chlorotic
condition which made the leaves appeared ‘netted’ (Fig.
5A). The ‘netted’ leaves turned pale green to whitish-yel-
low (Figs. 5B & C); drooped while the rest of the mature
green leaves remained upright.
As deciency persisted, the mature leaves developed
similar symptoms and became necrotic at the tip; caus-
ing the leaf to wither and die.
Fig. 5A Fig. 5B
Fig. 5C
... Specifically for cow grass, however, Chin (2013) recommended N:P:K ratio of 4:1:2. In other words, the demand for N by cow grass is two times more than K and four times more than P. SW204 supplied the highest amount of N on a per dry weight basis (Table 1). ...
Technical Report
Full-text available
The main purpose of this study were to determine whether two recycled materials, a wastewater treatment plant sludge (SW204) and a spent active carbon (SW411), were effective and safe to be used in the environment as a soil conditioner and to increase plant growth. Two test crops were used: kangkung (Ipomoea reptans) and cow grass (Axonopus compressus). Both crops were grown on three types of soils: a sandy clay loam, sandy clay, and clay soil. The soil treatments were NPK 15:15:15 fertilizer, NPK+SW204, and NPK+SW411, and they were applied at a rate of 1.5 t ha-1 for the NPK 15:15:15 fertilizer and 30 t ha-1 each for SW204 and SW411. The soil treatments were applied evenly onto the soil surface, and applications were done only once prior to planting. The field experiments were carried out under a rain shelter, with 5-mm daily watering of plants. Kangkung was planted in planting trays and the grass in polybags. Plastic bags were taped at the bottom of the planting trays and polybags to collect daily leachates. The kangkung experiment was carried out in two planting cycles (26 days for each cycle) and the grass experiment in a single planting cycle, lasting 89 days. Soil, plant, and leachate were analyzed for their nutrient (N, P, K, Ca, and Mg) and heavy metal (Sb, As, Ba, Zn, Cd, Cr, Cr6+, Co, Cu, Pb, Hg, Ni, Ag, Se, V, Mo, Tl, and Be) concentrations. The soils were also analyzed for soil pH, carbon content, and for several soil physical properties (bulk density, aggregation, aggregate stability, and soil water characteristics). SW204 and SW411 were found to be good soil conditioners. Both these organic materials were rich in N and K plant nutrients. Consequently, cow grass and kangkung had benefitted from the application of SW204 and SW411. The beneficial effects of SW204 and SW411 depended on the soil type. Overall, however, plant growth of kangkung and grass were the highest (in terms of their fresh and dry biomass weights) on soils treated with these organic materials. SW204 and SW411 were rich in N and K which suggest that they could be a good source of nutrients for oil palm, which has a high demand of N and K. Soils additionally treated with SW204 and SW411 also experienced lower P losses via leaching, compared with soils treated only with NPK fertilizer. In the grass experiment, SW204 and SW411 improved several soil physical properties, possibly due to the increased root and soil microbial activities that would in turn improve soil structure. The organic matter content in SW204 and SW411 were also high, and their addition into the soil had helped to increase the C content in the soil. Nonetheless, this study suggested that SW204 and SW411 would better be applied as a split application (i.e., applied frequently but in small doses) rather than as a single large dose. This is to reduce nutrient losses via leaching when not all their nutrients can be immediately used by the plants. To minimize P fixation, both SW204 and SW411 would also have to applied as close as possible to the plant roots. Finally, analysis of the 18 heavy metal elements in the SW204 and SW411, soils, plants (kangkung and cow grass), and leachate revealed that these heavy metals were either undetected or present in very small amounts that were very far below the maximum allowable levels according to Malaysia’s safety standards. The SW204 and SW411 also had undetectable presence of semivolatile and volatile organics, pesticides, PCBs, and miscellaneous (such as asbestos and furan). Consequently, this study has showed that SW204 and SW411 are safe to be applied as a soil conditioner.
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