Technical
“My Poa annua populations are in decline, whilst the perennial grasses, i.e. fescue and bent, are increasing”
hydrophobic organic molecules on individual soil particles. These substances may be released from decaying organic matter, soil fauna and micro-organisms. We should be asking ourselves; is it not possible these products have brought about a reduction in biological diversity which, in normal circumstance, would digest these conditions and is it not possible that these wetting agents might strip out some of the beneficial secretions associated with soil biota?
All hypothetical, but why are we seeing these types of products used with more regularity and as part of our annual maintenance programme today? I certainly did not use them, or need to, thirty years ago!
Looking back on the successes in Sussex all those years ago had me thinking and researching ways of producing a healthy environment for grasses to thrive naturally. I came upon the research work of Dr Elaine Ingham who has been studying the soil food web for many years. I was soon reading about compost tea applications, soil biology, its diversity and the important role it plays in plant health. The more I read into this subject, the more I realised this could be my “Get out of Jail” card! The key point in maintaining a healthy soil biology is quite simple, but most of us have been ignoring this fact and relying on inorganic fertilisers to supply nutrients or applying wetting agents or pesticides at the first signs of dry-patch or disease, all of which either bypass or harm the soil biology and results in a downhill spiral of plant health and vigour.
Soil biology and its role.
Like all living organisms, the soil biology that we are interested in has basic requirements, i.e. air, water, temperature and a food source. The ones we commonly associate with grass plants are bacteria, protozoa, nematodes and beneficial fungi, and there are thousands of species of each, all having their own niche in this extraordinary terrestrial world beneath our feet.
The size and composition of these
microbial populations are influenced by management practices affecting the soil environment, for example, cultural practices that decompact or aerate, creating aerobic conditions, or the lack of these operations or compaction-causing agents that result in anaerobic conditions. This diverse and complex community is 128 PC DECEMBER/JANUARY 2014
constantly at battle, consuming each other as a source of energy. Damage to any part of this complex community has long-term consequences for the remaining communities and could inflict imbalances that provide opportunities for pests and diseases. However, with this realisation, and what I have learnt in recent years, I am aware that Poa annua is dominating our swards all too easily and the main reason given is the increase in traffic, not just golf traffic but maintenance traffic. My golf rounds per year have increased from 35,000 to 40,000. Unfortunately, that additional golf traffic is predominantly the occasional golfer created by cut-price green fees, who hack their way around the golf course and lack even basic golf etiquette! Yet, my Poa annua populations are in decline, whilst the perennial grasses, i.e. fescue and bent, are increasing. How could this be? I have always aerated on a regular basis, my maintenance programmes have changed very little, yet there is a noticeable increase in perennial grass populations. I mentioned earlier that annual plants
require little association with soil biology and are usually interrelated with bacterial dominant soils. When you consider that, if we provide Poa annua with food and water, it will flourish, it is also well documented that bacteria populations, however small, will generally survive/recover in a fairly toxic environment. By toxic, I refer to the use of pesticides and, to a degree, inorganic fertilisers.
Artificial fertilisers with a high salt index
are harmful to all soil biology, however, bacteria can recover from such applications, but they are always getting knocked back, resulting in low population numbers. This is why managers who are on high nutrient programmes, which bypass the biology, will generate higher volumes of thatch, what I term as grass factory management! And, since, we have caused the reduction in microbial decomposition and, therefore, reduced Mother Nature’s means of decomposition; this results in excessive thatch, creating more work in terms of thatch removal by hollow coring and/or additional dressings of sand to dilute that thatch, both of which disrupt play. We then get into that downhill spiral and finish up managing predominantly Poa annua by applying more nutrients, more pesticides, producing shallow root systems and applying more wetting agents to
control thatch hydrophobicity. And, whilst all this is going on, we are seeing the desirable perennial grasses smothered because they cannot survive in a bacterial dominant environment. For years, I gave up on overseeding my
greens, since I assumed the competition by the mature grasses too high, but now I realise the perennial seedlings could not survive in a bacteria dominant environment that favoured annual grasses. It is important to remember that
perennial grasses cannot survive without a diverse biology, one that contains beneficial fungi. Equal amounts of bacteria and fungi would see perennial grasses compete against annual grasses and, assuming the rootzone received regular aeration and suitable food sources, the appropriate biology would proliferate. In a healthy soil, as much as 95% of plant species have a symbiotic relationship with soil fungi. Some of the fungi will send hypha (roots) for many metres, whilst other beneficial fungi are much smaller and live in close proximity to roots. They all live in close association with plants, searching for moisture and nutrients, digesting organic matter and even protecting plants against disease by producing antibiotics in exchange for sugars and carbohydrates. Unfortunately, beneficial fungi are more delicate and easily damaged by pesticides, which is why we are seeing an increase in bacterial dominant soils and, sadly, dominance in Poa annua. I now overseed my greens and see seedlings maturing, and my sward is gradually changing to one of perennial dominance.
Some managers would consider brewing as too expensive and I admit there is an element of truth in this, but I think this is largely down to some suppliers making the process more expensive by recommending unnecessary add-ons. Some managers are of the opinion it is too time consuming and messy and, again, this can be true, but there are various choices out there, some I have used and some I would never consider using.
Brewing methods
The common description for compost tea brewing is based upon extracting microbiology and nutrients from compost, aerated in a suitable container, fitted with a constant fine air bubble aerator and using clean water (chlorine removed) for a specific period of time. Every brew will finish differently since the actual brewing
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156